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Abstract
Energy consumption all over the world is increasing rapidly and there is pressing need to develop ways to conserve energy for future generation. The conventional refrigeration system consumes consumes very large amount of power.( power.( about 1.5 KW). lso for cooling! Evaporative coolers are are the better better option. The cost of Evaporative coolers is low and also it consumes less power than that of ". The main drawbac# of Evaporative cooler is that that the air supplies by it has very large amount of $umidity. %ue to which when an individual sits in the air of evaporative coolers ! he fills stic#iness on his body which is not comfortable condition. &o this pro'ect wor# invoves the manufacturing and design of the split unit which will not increase the humidity of air. t will maintain maintain the room at comfort conditions by recirculating the air in the room through &plit &plit nit.
CHAPTER 1: INTRODUCTION
1.1 INTRODUCTION OF EVAPORATIVE COOLING The evaporative cooler was the sub'ect of numerous .&. patents in the twentieth century* many of these! starting in 1+,-! suggested or assumed the use of ecelsior (wood wool) pads wool) pads as the elements to bring a large volume of water in contact with moving air to allow evaporation to occur. typical design! as shown in a 1+/5 patent! includes a water reservoir reservoir (usually with level controlled controlled by a float valve)! valve)! a pump to circulate water over the 1
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ecelsior pads and a s0uirrelcage fan to draw air through the pads and into the house. This design and this material remain dominant in evaporative coolers in the merican &outhwest! &outhwest ! where they are also used to increase humidity. Energy consumption all over the world is increasing rapidly and there is a pressing need to develop ways to conserve energy for future generations. 2esearchers are forced to loo# for renewable renewable sources of energy energy and ways to use available available sources sources of energy energy in a more efficient efficient way. "onventional refrigeration based vapour compression air conditioning systems consume a large portion of electrical energy produced produced mostly by fossil fuel. ndia3s energy demands are epected to be more than double by 4,,! and there is a pressing need to develop ways to conserve conserve energy for future future generations. generations. This implies implies that we have to loo# for renewable sources of energy and use available sources of energy in a more efficient way. Thus energy consumption can be reduced drastically by using energy efficient appliances. n ndia! the nion ministry of power6s research pointed out that about 4,457 of the total electricity utili8ed in government buildings in ndia is wasted due to unproductive desi design gn!! resu result ltin ing g in an annu annual al ener energy gy rela relate ted d fina financ ncia iall loss loss of abou aboutt 2s 1.5 1.5 bill billio ion. n. "onventional heating ventilation and air conditioning systems consume approimately 5,7 of the building energy. "onventional refrigeration based vapour compression air conditioning systems consume a large portion of electrical energy produced mostly by fossil fuel. This type of air conditioning is therefore neither eco friendly nor sustainable.
1.2 BASIC PRINCIPLES Evapor Evaporati ative ve coolin cooling g is a physica physicall phenom phenomeno enon n in which which evaporation evaporation of of a li0uid! typically into surrounding air! cools an ob'ect or a li0uid in contact with it. 9atent heat! heat! the amount of heat that is needed to evaporate the li0uid! is drawn from the air. When considering water water evapor evaporati ating ng into into air! air! the wetbulb wetbulb temperature temperature!! as comp compar ared ed to the the air6 air6ss drybulb temperature! is temperature! is a measure of the potential for evaporative cooling. The greater the difference between the two temperatures! the greater the evaporative cooling effect. When the temperatures are the same! no net evaporation of water in air occurs! thus there is no cooling effect. 2
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simple simple eample eample of natural evaporative evaporative cooling cooling is perspiration is perspiration!! or sweat! which the body secretes in order to cool itself. The amount of heat transfer depends on the evaporation rate! however for each #ilogram of water vapori8ed 445: #; of energy are transferred. The evaporation rate in turn depends on the humidity of humidity of the air and its temperature! which is why one6s sweat accumulates more on hot! humid days< the perspiration cannot evaporate.
Figr! 1.1 Basic "r#c!ss #$ !%a"#rati%! c##&i'g
Evaporative cooling is not the same principle as that used by =apourcompression refrigeration units! although that process also re0uires evaporation (although the evaporation is cont contai aine ned d with within in the the syste system) m).. n a vapo vapourcom rcompres pressio sion n cycle! cycle! after after the refrige refrigeran rantt evaporates inside the evaporator coils! the refrigerant gas is compressed and cooled! causing it to return to its li0uid state. n contrast evaporative coolers water is only evaporated once. n a spacecooling unit the evaporated water is introduced into the space along with the now cooled air* in an evaporative tower the evaporated water is carried off in the airflow. Key evapor evaporati ative ve coolin cooling g perfor performan mance ce descrip descriptor torss includ includee saturati saturation on effect effective ivenes nesss and unit unit efficiency. Effectiveness Effectiveness is defined as<
.... e0 1
Where! ε > Effectiveness (7) tdb > ?utdoor dry bulb temperature 3
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twb > ?utdoor wet bulb temperature ts > &upply dry bulb temperature n contra contrast st to vapour vapour compre compressio ssion n air condit condition ioners! ers! which which general generally ly dehum dehumidi idify fy indoor air! evaporative coolers add moisture to the supply air stream.
1.( S)STE* T)PES The evaporative cooling is done in various stages is mentioned as follows<
Si'g&! Stag! S+st!,s
&inglestage (direct) evaporative coolers generally combine a blower! a pump! an absorbent absorbent evaporative evaporative pad! and other components components in a metal! fiberglass! fiberglass! or polymer polymer cabinet cabinet that has an air inta#e and a supply air outlet. Water is circulated by the pump from a sump in the bottom of the cabinet over the evaporative pad! and the blower draws in outside air! passing it through the moist pad and into the building to be cooled. Wa Water ter lost through evaporation is replaced by the operation of a float valve (or a solenoid valve and float switch) that feeds in fresh water from a water supply. The direct evaporative cooling process is illustrated in @igure 1(%irect (singlestage) Evaporative "ooler irflow Aath). &ome single stage coolers do not use a pump but rotate the evaporative pads through a water bath. 2arely! a cooling pad is not used and the air is passed through a water spray.
Figr! 1.2 Dir!ct -si'g&!stag!/ E%a"#rati%! C##&!r Air$� Pat
There are other variations on this theme! but the principal of operation is the same. Because the continuous evaporation of water concentrates minerals in the sump water! some method of removing the minerals must be used. This is typically accomplished by either bleeding off a small percentage of the water that leaves the pump to a drain! or by 4
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periodically completely emptying the sump using a separate pump or electrically operated drain valve. T0#Stag! S+st!,s
ndirectC%irect (twostage) evaporative cooler designs add an indirect cooling stage upstream of the direct stage. The indirect stage! most commonly a plastic plate airtoair heat echan echanger ger!! cools cools the outdoo outdoorr air evapor evaporati ativel vely y! but withou withoutt adding adding moistu moisture re ( @igure @igure 4 ndirect %irect(Two&tage) Evaporative "ooler irflow Aaths). The downstream direct stage further cools the air! in some cases to a temperature below the outdoor wetbulb temperature! resulting in an overall effectiveness greater than 1,,7. Two stage systems deliver cooler and drier supply air than can be achieved with a singlestage cooler! but at the epense of some added fan and pump energy. ndirectonly evaporative coolers are sometimes used to precool ma#eup air for larger commercial buildings! but are not addressed by this proposed standard. There are currently two! twostage products on the mar#et. Aerformance of twostage systems can can be char charact acter eri8e i8ed d eith either er by thei theirr indi indire rect ct and and dire direct ct effe effecti ctive vene ness ss or by an over overall all evaporative effectiveness for the two stages. ?verall effectiveness can be used to compare single and twostage systems and is a preferred metric for standards purposes.
Figr! 1.( I'ir!ct Dir!ct-T0#Stag!/ E%a"#rati%! C##&!r Air$� Pats
&everal manufacturers offer portable or spot coolers that are designed to deliver cool air directly on the wor# area. These do not connect to an outside air supply and therefore are 5
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not appropriate appropriate for general building building cooling since they would eventually add moisture moisture until indoor air reaches saturation. The proposed standard would not apply to these products.
E%a"#rati%! *!ia
"ooler effectiveness depends largely on the capability of the evaporative pads or Dmed Dmedia ia to prov provid idee a high high wett wetted ed surfa surface ce area area and and minim minimal al airfl airflow ow resis resista tanc nce. e. Fany Fany materials have been used for media! including natural and synthetic fabrics.
T+"! S+'t!tic Natra& *at!&&ic
*!ia Epanded paper! and woven plastic. wood ecelsiors* rigid cellulose media* aspen pads copper copper!! bron8e bron8e or galvan galvani8ed i8ed screeni screening* ng* vermic vermiculi ulite! te! perlite!
Arior to the advent of rigid cellulose media! Daspen pads were the standard for production coolers. This material is made from aspen wood ecelsior from young young trees grown at altitudes above about 1,!,,, feet to avoid a fungus commonly found at lower altitudes. spen pads generally cool supply air to lower temperatures than competing materials! but have a short service life due to sagging! clogging and decay. woven! epanded paper product has gained popularity as a replacement for aspen wood pads in many mar#ets. This medi mediaa has has a long longer er usef useful ul life life than than aspen aspen wood wood!! but but does does not not cool cool air air as effe effect ctiv ively ely.. %eveloped in the 1+-,3s! rigid media proved to be a landmar# brea#through due to its high performance and comparative durability. This cellulose or fiberglass content material is bonded in a crossfluted design that induces turbulent miing of air and water for improved heat heat and moistu moisture re transf transfer er and selfcl selfclean eaning ing.. @irst @irst introd introduce uced d in large large commer commercial cial and indust industrial rial applica applicatio tions! ns! in recent recent years years the materia materiall has been been adopte adopted d by leadin leading g cooler cooler manufacturers for use in premium 0uality products.
1.3 APPLICATIONS Evaporative coolers are used in residential! commercial! agricultural! and industrial pplications where higher indoor humidity is acceptable and low operating cost is important. They can provide comfort e0uivalent to vapour compression cooling systems in dry climates!
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but during periods of hot! humid weather they may produce indoor conditions conditions that are outside the &$2E Dcomfort 8one shown in @igure and described (G).
Figr! 1.3 ASHRAE c#,$#rt 4#'! cart
"ommon mounting locations for singlestage units include walls! roofs! windows! and ground e0uipment pads. They will not function properly if the building is not supplied with a means of relieving indoor air to the outside. The preferred method of relief is to install barometric dampers in the ceiling or walls. ?pen windows or doors are fre0uently used for relief relief with with low cost cost wallCw wallCwind indow owmou mounte nted d system systems! s! and agricu agricultu lturalC ralCind indust ustrial rial system systems. s. "eilingmounted relief dampers in houses with attics have the advantage of cooling the attic as well as the house! reducing ceiling heat gain. Fanufacturers generally tend to oversimplify si8ing methods by specifying airflow 2ate that corresponds to a particular location or design wet bulb temperature. Fore accurate techni0ues techni0ues calculate building cooling cooling load eclusive of latent and infiltration infiltration loads! and specify a system that will deliver a sufficient volume of air to meet the design load based on 7
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the corresponding design supply air temperature and the desired indoor air temperature. The supply air temperature is calculated from the system effectiveness and the design wet bulb temperature temperature as indicated indicated in E0uation E0uation 1. 9atent cooling cooling load can be ignored ignored because all air is ehausted* infiltration load can be ignored because the evaporative cooler pressuri8es the building. Evaporative coolers are typically controlled using manual manual switches! timers! and thermostats. Their low operating cost and relatively low cooling capacity favor the use of low cost cost contro controls ls rather rather than than the setbac# setbac# thermo thermostat statss used used with with vapor vapor compre compressio ssion n coolin cooling g systems. &ome evaporative coolers have two fan speeds or fully variable fan speed control! allowing the user to control the temperature to some s ome etent via the supply airflow! ma#ing the capacity of these units variable. &ome of the important applications of Evaporative cooling are eplained as under< H "??9IJ< Two Two common applications of evaporative cooling are< 1) To improve the environment for people! animals or processes! processes ! without attempting to "ontrol ambient temperature or humidity. humidity. 4 To improve ambient condition in a space. $F%@"T?I< 1) sing re circulated water without prior treatment of the air. 4) Areheating the air and treating it with recirculated water ) sing heated water H %E$F%@"T?I I% "??9IJ< Evaporative coolers are also used to cool and dehumidify air. $eat and moisture are removed from the air. @or this! the temperature of water be lower than %AT of the Entering air. H 2 "9EIIJ< Evap Evapor orat ativ ivee cool cooler erss of all all type typess perfo perform rm some some air air clea cleani ning ng.. The The dust dust remo remova vall efficiency of evaporative coolers depends largely on si8e and density of dust. They are ineffective in removing smo#e. H FKEA 2< n most industrial plants and in all confined spaces! ma#eup air is re0uired to replace the large volumes of air that must be ehausted to provide the re0uired conditions for
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personal comfort! safety! process operations and to maintain high indoor air 0uality. Evaporative cooling is useful for that. H "?FFE2"9 "??9IJ< n dry climate! evaporative cooling is effective with lower velocities that are re0uired in humid climates. This ma#es it suitable for use in applications where low air velocity is desirable. I%&T29 I%&T2 9 AA9"T?I&< AA9"T?I&< a) n a factory having a larger internal heat load! it is difficult to approach outdoor condit condition ionss during during the summer summer withou withoutt using using an etrem etremely ely large large 0uanti 0uantity ty of outsid outsidee air. air. Evaporative cooling can alleviate this heat load problems and contribute to wor#er efficiency. b) rea "ooling< Evaporative cooling of industrial buildings may be accomplished on an area basis or by spot cooling. c) &pot "ooling< &pot "ooling yields to more efficient use of e0uipment when the personnel are relatively stationery. t is applicable in hot areas where individual cooling is needed such as chemical plants! pig and ingot casting! die casting shops! glass forming machines etc. d) 9aundry< 9aundry< ?ne of the most difficult difficult or severest applications applications of evaporative evaporative cooling is laundries! since heat is also produced by the processing e0uipment. properly designed evaporative cooling system reduced the temperature in a laundry from , " to -, " below outside temperature. e) "ooling of large motors< The rating of electrical generators and motors is generally based on a maimum ambient temperature of /,, ". @or a temperature higher than this! ecessive ecessive temperature will develop in the electrical windings windings unless the load is reduced. n air supplied to the motorCgenerator is through evaporative cooler! they are operated safely without load reduction. f) Jas turbine turbine operat operation ion<< gas turbines turbines re0uire re0uire a large large 0uantity 0uantity of clean clean cool cool air (generally -,/, #g C#W hr).Evaporative cooling is useful in serving this purpose. g) Arocess Arocess cooling< cooling< n the tobacco! tobacco! tetile! tetile! spray coating coating and other ndustries ndustries where manu manufac factu turin ring g re0ui re0uire ress accu accura rate te humi humidi ditie ties! s! comf comfor ortt cool coolin ing g is also also obta obtain inab able le by evaporative coolers. $igh relative humidities are re0uired in cigar plants! tetile etc. and evaporative cooling will provide the solution.
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h) Fine cooling< in mine evaporative cooling with mechanical refrigeration is used to produce desirable conditions. i) @ruit and =egetables< Evaporative cooling as it is applied to fruits and vegetables is to provide an effective yet inepensive means of improving common storage. Evaporative cooling is used as a supplement to refrigeration in the storage. Evaporative cooling can be used effectively to store Aotatoes! pples! pples! ?ranges! 9emons etc.
1.5 ADVANTAGES ADVANTAGES AND AND DISADVA DISA DVANTAGES NTAGES OF EVA EVAPORATIVE COOLERS ADVANTAGES:
1) ts initial and running cost is low. 4) nli#e air conditioners! air coolers do not re0uire refrigerants and hence ecofriendly. ) t is comparatively less bul#y. /) ts maintenance cost is low. 5) Io separate electrical connections are re0uired for installing an air cooler. t can wor# at normal voltage and fre0uency. -) Aower consumption is low. :) %anger of lea#age of toic refrigerant is not present. G) The epensive insulation for the walls! ceiling etc. is not re0uired. +) %esert coolers can be conventionally placed in open space such as corridors! balcony! balcony! verandahs! etc. 1,) Tightness Tightness of doors and windows are not re0uired while using desert coolers.
DISADVANTAGES:
1) $umidity control is not possible. 4) t cannot be used effectively in regions with high humidity. humidity. ) t may not be suitable for people suffering from rthritis! Bronchitis! sthma! etc.
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/) fter regular intervals! the cooling pads have to be changed and the tan# has to be cleaned. 5) The parts coming in contact c ontact with humid air may corrode. Though the disadvantages cannot be neglected! but the advantages overcome these disadvantages and ma#e them so popular nowadays.
1.6 CO*PARISON OF EVAPORATIVE EVAPORATIVE COOLING TO AIR CONDITIONING ADVANTAGES: L!ss !7"!'si%! t# i'sta&&
Estimated cost for installation is about half that of central refrigerated air conditioning.
L!ss !7"!'si%! t# #"!rat!
Estimated cost of operation is 1C/ that of refrigerated air.
Aower consumption is limited to the fan and water pump vs. compressors compressors!! pumps pumps and and blowers blowers..
Eas! #$ *ai't!'a'c!
The only two mechanical parts in most basic evaporative coolers are the fan motor and the water pump! both of which can be repaired at low cost and often by a mechanically inclined homeowner. homeowner.
V!'ti&ati#' air
The constant and high volumetric flow rate of air through the building reduces the ag!#$ air in the building dramatically. dramaticall y.
Evaporative Evaporative cooling cooling increases increases humidity humidity!! whic which! h! in dry dry clim climat ates es!! may may impr improv ovee the the breathability of the air.
The pad itself acts as a rather effective air filter when properly maintained* it is capable of removing a variety of contaminants in air! including urban o8one o8one caused caused by pollution! 11
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regardless regardless of very dry weather. weather. 2efrigeration 2efrigerationbased based cooling systems lose this ability whenever there is not enough humidity in the air to #eep the evaporator wet while providing a constant tric#le of condensate that washes out dissolved impurities removed from the air. DISADVANTAGES: P!r$#r,a'c!
$igh dewpoint (humidity) (humidity) conditions conditions decrease the cooling cooling capability capability of the evaporative evaporative cooler.
Io dehumidification dehumidification.. Traditional air conditioners remove moisture from the air! ecept in very dry locations where recirculation can lead to a buildup of humidity. Evaporative cooling adds moisture! and in dry climates! dryness may improve therm thermal al comf comfort ort at at higher temperatures.
C#,$#rt
The air supplied by the evaporative cooler is typically G,+,7 relative humidity* very humid air reduces the evaporation rate of moisture from the s#in! nose! lungs! and eyes.
$igh humidity in air accelerates corrosion corrosion!! particularly in the presence of dust. This can considerably shorten the life of electronic and other e0uipment.
$igh humidity in air may cause condensation condensation.. This can be a problem for some situations (e.g.! electrical e0uipment! computers! paperCboo#s! old wood).
8at!r
Evaporative coolers re0uire a constant supply of water to wet the pads.
Water high in mineral mineral conte content nt will leave mineral deposits deposits on the pads and interior interior of the cooler. Bleedoff and refill (purge pump) systems may reduce this problem.
The water supply line may need protection against free8e bursting during offseason! wint winter er tempe temperat ratur ures. es. The The cool cooler er itsel itselff need needss to be drai draine ned d too! too! as well well as clean cleaned ed periodically and the pads replaced.
*isc!&&a'!#s 12
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?dours and other outdoor contaminants may be blown into the building unless sufficient filtering is in place.
sthma patie atien nts
may
need eed
to avoi avoid d
poor poorly ly
maint aintai ain ned
evap evapor orat ativ ivel ely y
coo cooled led
environments.
sacrificial anode may anode may be re0uired to prevent ecessive evaporative cooler corrosion.
Wood Wo od wool w ool of of dry cooler pads can catch fire even by small spar#s.
1.9 SCOPE OF 8OR
The evapor evaporati ative ve cooler cooler cools cools air by evapor evaporati ative ve action action!! but the main main drawba drawbac# c# of evaporative cooler is that it increases the humidity of incoming air. $umidity of air is net content of water in dry air. This humidity causes stic#iness on the body of individual which ma#es him uncomfortable when anyone sits in the environment for long time* this is the main problem of evaporative cooler. To overcome the problem people move to an air conditioner! but the " is very epensive and it consumes large amount of power
(about 1.5 KW). Thus it is not affordable to the common man. The goal of this pro'ect pro'ect is to reduce reduce to amount amount of humidity humidity in the outlet outlet air of evaporative cooler so that the air will be comfortable to individuals who are in the vicinity of the air. lso to supply the air in less cost so that common man can also afford the the cool cooler er.. This This goal goal can can be achi achiev eved ed by cons constru truct ctin ing g a duct duct in whic which h three three heat heat
echangers will be placed and water from evaporative cooler will be supplied to them and the air will be supplied through this duct to room. Thus the target of reducing humidity of air will be achieved. This unit re0uires two fans! three pumps* with total
consumption of 1,W thus the unit is affordable to common man. To achieve achieve less power consumption consumption of cooler we have done survey of less power fans in various dealers of ;algaon city and we have selected 1GW fans. Then while selection of heat echangers we have selected 4 pass copper tube pipe heat echangers with dimension 14L1, inch.
CHAPTER 2: LITERATURE REVIE8 13
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2.1 INTRODUCTION fter eploring all the possibilities in the areas in which the temperature level is as high as that cannot be tolerated for survival of beings and ;algaon coming under the highest temperature 8one in Faharashtra! we had come to the conclusion that our findings in ma#ing evaporative cooler in split unit would certainly be helpful to the inhabitants of the area not only for controlling the humidity level in the areas bound for accommodation but also for the industries where this coolers can be utili8ed for the commercial purposes. hereby give the contetual references of the former scientist in the field who have completed their research and find it a convenient reference which is attached herewith for your #ind perusal.
2.2 LITERATURE REVIE8 The following research views are considered for achieve our ob'ective as follows< T. Ra%i ira' ; S.P.S. Ra<"t in (4,1/) paper they have focused on energy re0uirements of
the world and further added that Energy consumption all over the world is increasing rapidly and there is a pressing need to develop ways to conserve energy for future generations. 2esearchers are forced to loo# for renewable sources of energy and ways to use available sources of energy in a more efficient way. "onventional refrigeration based vapour compression air conditioning systems consume a large portion of electrical energy produced mostly by fossil fuel. novel dew point evaporative cooler (%AE") can sensibly cool the incoming air close to its dew point temperature. n this paper feasibility of %AE" system is investigated for various ndian cities for office buildings during day time. @irstly the weather data of different cities of ndia is used to find the suitability of dew point technology for ndian buildings by estimating the cooling capacity of the cooling system for each city. &econdly energy saving potential of the dew point cooling system w. r. t. to the conventional compression based air conditioning system for different cities of ndia is estimated.
Ca&i$#r'ia E'!rg+ C#,,issi#'; I' tis "a"!r they have wor#ed on increasing efficiency of
cooler cooler.. %avis %avis Energy Energy Jroup Jroup has develo developed ped a DJener DJenerati ation on indire indirectd ctdire irect ct evapor evaporativ ativee cooler (%E") with support from the "alifornia Energy "ommission3s AE2 program. The unit combines advances in airflow configuration with manufacturing improvements to reduce 14
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costs and improve efficiency and reliability. 9i#e earlier generations! the new %E" uses a highly efficient electronically commutated motor and electronic controls. The system features the following improvements< H low pressure drop counterflow indirect heat echanger that precools secondary air and is capable of effectiveness values greater than :,7. H dvanced heat echanger plates that are modular and manufactured costeffectively on an inline thermoformer. H lea#proof rotationally molded cabinet with integral topmount blower and underside water reservoir. H reliable! lowenergy sprayless water distribution system. 9aboratory testing! supervised by 9awrence Ber#eley Iational 9aboratory! demonstrates that this new %E" unit performs with total effectiveness ranging from 1,+7 and 11-7! varying inversely with blower speed. The test unit outperformed both prior generations! thereby eceeding pro'ect performance goals. Feasured energy efficiency ratios (EE2) ranged from /, to 1-! again varying inversely with blower speed. @ull year performance simulations based on the test data indicate G+ to +57 %E" annual energy savings
Cc= tsc!r -2>1(/. This paper reports The use of conventional evaporative cooling has
rapidly declined in the nited &tates despite the fact that it has high potential for energy savings in dry climates. Evaporative systems are very competitive in terms of first cost and provide significant reductions in operating energy use! as well as pea#load reduction benefits. &ignificant mar#et barriers! such as the cost of the prototype evaporative cooling systems systems and consumer perceptions perceptions of evaporative evaporative coolers being unable unable to maintain comfort comfort condit condition ions! s! still still remain remain and can be address addressed ed throug through h improv improved ed system systemss integr integrati ation! on! including the following< H nnovative components H Better design of supply ducts and dampers H dentification of best climates for full cooling season comfort control and potential limits imposed by a rainy season
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H %eve %evelo lopm pmen entt of util utilit ity y part partne nersh rship ipss to roll roll out out evap evapor orat ativ ivee cool coolin ing g syste system m desig design n parameters for production builders.
This report investigates the first of these approaches! eploring innovative components. The .&. %epartment of Energy (%?E) Building merica research teams are investigating the use of two promis promising ing new pieces pieces of residen residentia tiall coolin cooling g e0uipm e0uipment ent that that employ employ evapor evaporati ative ve cooling as a part of their system design. The ?&ys unit shown in @igure 1! which is a combination of direct and indirect evaporative cooling stages developed by %avis Energy Jroup (%EJ) and manufactured by &pea#man "2&! is used to ultimately provide outside air to the living space *#i!' Far,ai'i Faraa'i; Gass!, H!iari'!
results of an investigation on a twostage cooling system have been studied. This system consists of a nocturnal radiative unit! a cooling coil! and an indirect evaporative cooler. %uring the night in summer! re0uisite chilled water for a cooling coil unit is provided by nocturnal radiative cooling and is stored in a storage tan#. %uring the net day! the water in the tan# provides chilled water for the cooling coil unit and hot outdoor air passes through twostages< the cooling coil unit and an indirect evaporative cooler. Three sources provide secondary air for the indirect evaporative cooler. The sources are outdoor air! the air leaving from from the the cool coolin ing g coil coil!! and and the the air air leav leavin ing g from from the the indi indire rect ct stag stagee (rege (regene nerat rativ ive). e). The The investi investigat gation ion has been been conduc conducted ted in weathe weatherr condit condition ionss in the city Tehra Tehran. n. The The results results obtained demonstrate that the first stage of the system increases the effectiveness of the indi indire rect ct evap evapor orat ativ ivee cool cooler er.. lso! lso! the the regen regener erati ative ve model model prov provid ides es the the best best comf comfor ortt condit condition ions. s. Theref Therefore ore!! this this enviro environme nmenta ntally lly friendl friendly y and energ energye yeffi fficien cientt system system can be considered as an alternative to the mechanical vapor compression systems.
ASHRAE '# (>25 R.H. Tr' r'!r !r This paper focuses on potential applications of evaporative
coolin cooling g (E") (E") and an associa associated ted survey survey of research research re0uirem re0uirement entss of E" as suppli supplied ed in residential and small commercial buildings. To prepare this wor#! the literature in the field was reviewed and people active in the field were contacted. &iteen recommendations are presented and described in the paper including institutional issues! appropriate roles for E" systems! systems! necessary necessary analysis analysis and testing! proper proper application applications! s! and hardware developmen developmentt 16
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needs. These recommendations represent composite opinions from the literature review and phone conversations as analy8ed by the authors. There are potential applications for E" system systemss and related related research research issues that that are not fully fully under understo stood od by most most govern governmen mentt agencies! utility companies! engineers! industries! decision ma#ers! and the consuming public. $owever! as energy costs rise there will be increasing demand for operationally inepensive coolin cooling g system systems. s. Thus! Thus! informatio information n on the potent potential ial of E" system systemss could could benefi benefitt these these parties.This paper focuses on residential and small commercial building applications of E". Fost of the published technical wor# in the E" field has been done for large industrial and commercial building applications! but in no way do these analyses! systems! and approaches general generally ly pertai pertain n to residen residential tial buildi buildings ngs.. $owev $owever! er! these these papers papers and report reportss have have been been collected and reviewed to assess available techni0ues and conditions under which they might have residential applications. %ue to economy of scale! the largesystems are often able to employ epensive peripheral e0uipment and ductwor#! which is not costeffective in smaller buildings. lso! commercial systems generally receive scheduled maintenance! in ecess of the norm for residential units. Thus the problems and solutions of residential E" systems separate from large commercia 6systems are worthy of study. The intent of this paper is to recommend what research is re0uired to identify appropriate roles for residential E" systems! describe necessary analysis and testing! place applications into proper technical and economic perspective! and improve components! systems! hybrids! and applications
Ri' )'; )'; )'# )'# H0a'g; R!i'ar Ra!r,ac!r ! n this study the seasonal performance
of a resi reside dent ntial ial air cond condit itio ioni ning ng syst system em havi having ng eithe eitherr a fina finand ndt tub ubee cond conden enser ser or a microchannel condenser is eperimentally investigated. Ficrochannel heat echangers offer a higher volumetric heat echange capacity and a reduced refrigerant charge amount. $owever! the the opera operati ting ng chara charact cteri eristi stics cs and and the the seaso seasona nall ener energy gy effi efficie cienc ncy y ratio ratio (&EE (&EE2) 2) of the the residen residential tial air condit condition ioning ing system system using using a microc microchan hannel nel conden condenser ser have have not been been well well #nown. #nown. @or this this investi investigat gation ion!! a commer commercial cially ly availa available ble : #W capacit capacity y residen residential tial air conditioning system having a finandtube condenser served as the base system. fter testing the base unit with the finandtube condenser! the condenser was replaced by a microchannel heat echanger echanger with the same face area under identical test conditions conditions.The .The test results show 17
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Air cooler with Split Cooling Unit
that the system with a microchannel heat echanger has a reduced refrigerant charge amount of 1,7! the coefficient of performance increased by -7 to 1,7! and the &EE2 increased by :7 as compared with those of the base system. Foreover! the condensing pressure of the system is decreased by 1,, #Aa and the pressure drop across the condenser is decreased by G/7. The microchannel heat echanger enhances the &EE2 of the residential air conditioning system by providing better heat transfers at reduced pressure drops. R. Ra0a Ra0a'g 'g= =&; &; ?. ! !ar ari; i; ?. Hir Hir'& '&ab ab a' a' B.@! B.@!g g,a ,ati ti -/; n this this Aape Aaper r the
dehumidification process is important especially especiall y in hot and humid countries! such as Thailand since it helps to improve 0uality and 0uantity of products which are used in agriculture and industries. There are number of methods available to achieve this process! but among all %esic %esicca cant nt meth method od is 0uit 0uitee bene benefi fici cial al for for envi enviro ronm nmen ent! t! sinc sincee it is not not invo involv lved ed with with fluorocarbons which may impact on o8one layer. n Thailand! the most commercial desiccant materia materials ls such as Silica gel ! Molecular sieves! sieves! Calcium chloride! chloride! Lithium chloride! chloride! etc. are imported from "hina. &ome Silica gel is produced in Thailand but is not ade0uate for local re0uir re0uireme ement nt as well well as for commercia commerciall point point of view. view. n additi addition on Calciu Calcium m chlori chloride de and Lithium chloride are toic for human being. Therefore finding another alternative which is cheaper and safer for environment to replace commercial desiccants! for applying in many applications of dehumidification is etremely essential. &ustainable materials li#e agricultural origin waste are receiving much interest worldwide to various reasons including economical! political etc. The ob'ective of this study is to develop a moisture adsorption isotherms model of "oconut coir (Cocos ( Cocos nucifera) nucifera) and to simulate long term performance of this material as desiccant under Bang#o# ambient conditions. Foisture adsorption isotherm of dried coconut coir is determined by the static method. sotherms are found to be of type = as per A" classification. ?swin e0uation is the best fitted e0uation for the eperimental data for young coir. The effect of Thailand environment condition for one year on temperature! relative humidity and moisture content in the surface of coconut coir material was simulated using a common software W@ 4% program. Moung coconut coir reveals that the average moisture adsorption capacity is about 4-7 dry basis! the average air relative humidity and temperature is about :7 and 4G.- o"! respectively. respectively. The maimum maimum moisture moisture adsorption adsorption capacity is :7 when air3s relative humidity is G,7. The determination of moisture adsorption isotherms which is! very important for the modeli modeli8ati 8ation on of coconu coconutt coir coir perfor performan mance ce and heat heat and mass mass transf transfer er correla correlatio tions ns were 18
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Air cooler with Split Cooling Unit
developed. The eperimental nalysis depicts that the adsorption isotherms of the coconut coir are of the type = following the A" classification. sotherms of type = indicate porous materials and wea# interaction. Mou Moung ng coconut coir is found to have the high performance for moisture adsorption. "oconut coir isotherm models were developped by using nonlinear regress regression ion techni techni0ue 0ues. s. "ompar "ompariso isons ns are made made on the basis basis of statist statistica icall errors. errors. ?swin3 ?swin3ss e0uation was the best fitted e0uation to the eperimental data for young coir. n case of the use of bed at ambient temperature application li#e a wall building component! the coconut coir chip bed longterm performance was simulated using a common software W@ 4% program. Moung Moung coconut coir reveals that the average moisture adsorption capacity is about 4-7 dry basis at the average air relative humidity and temperature of about :7 and 4G.-o"! respectively. The maimum moisture adsorption capacity is :7 when air relative humidity is G,7.
Hisa, Hisa, E&D!s E&D!ss# s#=+ =+;; Hisa, Hisa, Ett Ett#' #'!+ !+;; A
eperimental rig of twostage evaporative cooling unit is constructed and tested in theKuwait environment. The system is formed of an indirect evaporative cooling unit (E") followed by a direct evaporative cooling unit (%E"). The system is operated during the summer season of Kuwait with dry bulb temperatures higher than /5 N". The system is operated as a function of the pac#ing thic#ness and water flow rate of the %E" unit. ?ther parameters include thewater flowrate to the E" unit and the mode for operating the E" heat echangers. 2esults show that the efficiency of the E"C%E" varies over a range of +,14,7. &imilarly! the efficiency of the E" unit is varied over a range of 4,/,7. The efficiency of the %E" unit varies over a range of -+7. The data is used to correlate the Iusselt number for the air stream outside the E" heat echange unit. 2esults showthat the Iusselt number varies over a range of 15, /5,! which corresponds to a heat transfer coefficient of ,.1,./ #WCm4 K. These results are consistent with literature data and should be of great value in designing of E" units. n summary! summary! the results and analysis presented here indicate the attractiveness of the E" systems for indoor air conditioning. $igh efficiency is obtained irrespective of the high inta#e air temperature. t is highly recommended to continue research investigations in this area in search search for low energ energy y consum consumpti ption on air condit condition ioning ing units units as thesewo thesewould uld contri contribut butee to a cleaner environment andwould conserve the limited resources of fossil fuel.
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The performance of an eperimental unit for indoor air conditioning is evaluated in the hot and humid environment of Kuwait. The unit is composed of indirect and direct evaporative cooling units. Feasurements are made as a function of various operating and design parameters! which includes number of heat echangers in the E" unit! flow direction of water inside the E" heat echange units! flow rate of the air stream outside the heat echange units and across the %E" pac#ing! thic#ness of the %E" pac#ing! water flow rate across the %E" pac#ing. Feasurements include the air temperature across the evaporative cool coolin ing g unit unit as well well as the the water water flow rates rates in the the E" E" and and %E" %E" unit units. s. The The syst system em performance is reported r eported in terms of the temperature efficiency e fficiency!! which gives a measure for the cooling degrees of the ambient air. lso! the Iusselt number of the air stream across the E" heat echanger echanger is correlated as a function function of design and operating operating conditions conditions.. 2esults 2esults show that the efficiency of the E"C%E" varies over a range of +,14,7. This implies that the dry bulb temperature of the outlet air is lower than the wet bulb temperature of the ambient (or inta#e) air. &imilarly! the efficiency of the E" unit is varied over a range of 4,/,7! which is less than that of the %E" unit. The efficiency of the %E" unit varies over a range of - +7. &uch values are 0uite higher than those reported in literature for the standalone %E" systems! which commonly vary over a range of 5,:57. This is because of the cooling effect of the E" unit. lso! it should be noted that the efficiency of the E" is also lower than that for those reported in literature! which commonly vary over a similar range for the standalone %E" system. This is because results reported in literature are for an E" system combined with with an etern eternal al coolin cooling g tower tower.. $oweve $owever! r! in the system system studie studied d here! here! water water coolin cooling g is accomplished by the %E" unit only. only. The The Iusse Iusselt lt numb number er for for the the air air stream stream varie variess over over a rang rangee of 15, 15,/5 /5,! ,! whic which h corresponds to a heat transfer coefficient of ,.1,./ #WCm4 K. These results are consistent with literature data and should be of great value in designing of E" units. n summary! summary! the results results and analysis presented here indicate the attractiveness attractiveness of the E" systems for indoor air conditioning. $igh efficiency are obtained irrespective of the high inta#e air temperature. t is highly recommended to continue research investigations in this area in search for low energy consumption air conditioning units! as this would contribute towards a cleaner environment and would conserve the limited resources of fossil fuel.
2.( CONCLUDING RE*AR 20
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The humidity in the air of evaporative cooler ma#es the cooling space uncomfortable. This humidity ma#es evaporative cooler useless in humid regions. &o to ma#e the air of evaporative cooler comfortable following two processes must be done on it •
"ooling and $umidification "ooling it already does so important factor is dehumidification.
S"&it C##&i'g U'it &plit "ooling nit consist of three heat echangers. The temperature of water of the Evaporative cooler decreases gradually after starting the cooler. This cooled water is supplied to the &plit "ooling nit. When the air passes through the heat echanger! it losses its heat and cooled air of 45 o" is supplied to the room without increasing its humidity. This unit can be used in non coastal region.
CHAPTER (: S!&!cti#' #$ E%a"#rati%! C##&!r a' !sig' #$ S"&it U'it (.1 S!&!cti#' #$ E%a"#rati%! C##&!r The "ooler buyer finds it difficult to select the right cooler to suit his re0uirement because of his inade0uate #nowledge about coolers. t present! the mar#et is flooded with different brands of coolers! each one promising something new with large difference in prices. This further adds the confusion in the minds of buyer .Therefore the purchase is lastly made made on the the oute outerr fini finish sh and and manu manufac factu turer rer3s 3s recom recomme mend ndat atio ions ns.. Ece Ecept pt a few! few! most most manu manufac factu ture rers rs Them Themsel selve vess are are not not awar awaree of the the cool cooler er tech techni ni0u 0uee and and the the cool cooler erss are are manufactured with thumbrule occupied with minor changes. The following points should be #ept in mind by the purchaser. 1) $e should select the proper si8e of the cooler depending on the room volume to be cooled. The thumb rule is that the cooling capacity of the cooler should be e0ual to the room volume. f the room si8e is m O /m O m > - cubic m.! then the fan capacity should be cubic m. C min. This indicated one air change per minute. There must be cross ventilation 21
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whenever the cooler is fied. The fiing of the cooler outside the window is best. ?ne air change change per minutes is only with crossventilatio crossventilation! n! otherwise the cooler #ept inside the room will increase the humidity in the room after some time and will ma#e the room more uncomfortable. 4) The cooler fan and pump should be of correct specifications. Fostly substandard @an and pump are used for earning higher profits and even sold at lower price by the road side manufacturers. ) "hec# the internal fitting of cooler fan and pump. The fan blades should be properly centered in the front panel opening and should be mounted flush with front panel for effective cooling. /) "hec# the water spray system on the pads. The water droplets should fall on the pads uniformly for proper wetting of pads. The water should not fall towards the inner surface of the padas in this position! it is li#ely that the cooler fan will suc# the water droplets and will throw them with the air in the room and will spoil the carpet etc. The motor of the cooler fan and pump may burn due to constant water spray. 5) The The louv louvers ers (air (air inle inlets) ts) open openin ings gs shou should ld be mai maimu mum m poss possib ible le to avoi avoid d obstruction in suc#ing of air. This reduces the pressure loss and power consumption. -) The body of the cooler should of proper si8e to match the air delivery of the cooler fan . n smaller si8e body the air will be suc#ed at higher speed through the pads and will have less time in contact with the water and will not be properly cooled. The higher air delivery in smaller cooler body is therefore meaningless. The body of the air cooler should be made of proper gauge of steel to avoid vibration and noise. :) "hec# the proper earthing of the fan motor and pump motor before putting the point avoids the shoc#.
(.2 D!sig' #$ s"&it c##&i'g 'it The &plit cooling unit consist of three heat echangers echangers e0ually spaced in which chilled water is supplied from the Evaporative cooler by using a high pressure submersible water pump of /,W. /,W. fan of 1G W is fitted between the first and second heat echanger! as shown in figure. ?ne common rail is attached at the inlet of split unit which supplies the water to all three heat echanger at e0ual pressure while another common rail is attached at the outlet of heat echanger which collects the water from the heat echanger and supplies to the water tan# of Evaporative cooler. 22
Modifed Air cooler with Split Cooling Unit
Ass,"ti#': 1) nternal nternal diameter diameter of the the tube tube is 5mm(s 5mm(s per per available available in mar#et) mar#et) 4) Jap betw between een heat heat ech echang anger er is 1cm 1cm.. ) mbi mbient ent tem tempe perat ratur uree is /4o". /) Water ater tempera temperatur turee at startin starting g of unit unit is 4o". 5) "onduc "onductiv tivity ity of of "oppe "opperr is G-w G-wCm Cmo".
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&A9T "??9IJ IT
CHAPTER 3: THEORETICAL THE ORETICAL ANAL)SIS ANAL)SIS 3.1 INTRODUCTION To study the various parameters of split unit over the wide range of %BT! WBT P 2$ for inside and outside conditions.
3.2 SI*PLE THEORETICAL ANAL)SIS The The cool coolin ing g effi efficie cienc ncy y of evap evapor orat ativ ivee air air cool coolin ing g is measu measured red by the the satur saturat atio ion n effectiveness or the evaporative saturation efficiency (η) (&$2E &tandard! I&C&$2E &tanda &tandard rd 14, 14,,1) ,1).. t is determ determine ined d primar primarily ily by the measur measured ed tempera temperatur tures es of the air entering and eiting the rigid media using the following e0uation<
η>1,,O (Td1Td4CTd1Twb) Where! Td1 >inlet drybulb temperature (° (°"). Td4 >outlet drybulb temperature (° (°"). Twb>thermodynamic wetbulb temperature of the inlet air(° air(°")* R >evaporative saturation efficiency (7). The coefficient of performance of split unit and the evaporative cooler is given by 24
Q.e0 1
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Air cooler with Split Cooling Unit
"?A> h1h4Cw Where h1>heat of air at inlet h4> heat of air at outlet w> wor#done
t should be noted that the above e0uations consider the water vapour and not the water li0uid. The solid media can be be considered to simulate a heat heat echanger. "onse0uently the heat or mass transfer transfer coefficient coefficient can be calculated with log mean temperature temperature difference ∆T or density density difference difference of water vapour ∆ρv to proy 0 and in me E0uations (/) and (5) we obtain. h>0 Cs∆ Cs∆T
Q.e0 / 5
Where! h > heat transfer coefficient (W Cm4K) s> total wetted surface area of rigid media (m4)* and ∆T> the log mean temperature difference for a constant water temperature in the heat echanger! which is assumed to e0ual the wetbulb temperature.
CHAPTER 5: EPERI*ENTAL SETUP • • •
The new design is as shown in figure! it consist of following components The conventional evaporative cooler. duct consisting of three heat echangers and a fan to supply air. Two Two submersible pumps
The heat echangers are supplied with the cooled water from the Evaporative cooler by using high pressure submersible pump of /,W via fleible pipes. ?utlet water from all heat echangers is connected to the common rail and it collected in the water tan# of Evaporative cooler. This This water cools c ools Evaporativaly in the Evaporative cooler.
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5.1 8ORING •
@irstly the cooled water from water tan# of Evaporative cooler is supplied to the heat echangers via common rail. The temperature of water at inlet is 4/ o" for all heat
• • •
echangers. When air comes in contact with the heat echangers! it losses its heat. Then cooled air is supplied to the room without increasing increas ing its humidity. The The wate waterr at the the outl outlet et of heat heat ech echan ange gers rs is coll collec ecte ted d in the the wate waterr tan# tan# of
•
Evaporative cooler. The temperatures of outlet water from the third heat echanger 45.4 o"! 4/.: o" from
•
the second heat echanger and 4/.4 o" from first heat echanger. This This cool cooler er recir recircu culat lates es the the air air from from the the room room so its its cool coolin ing g effe effect ct will will go on increasing and it can maintain room temperature upto 45Sc. Total power consumption of the unit is 'ust 1,W. 1,W.
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Air cooler with Split Cooling Unit
Table Table 1< Temperature Temperature of air at various points of split nit &r
Time ime
Io
Temper mperat atur uree of air air at vari variou ouss poin points ts of spli splitt nit nit 1
4
/
5
-
Troom
Tamb
1
+.,,am
4+.1
4+.
4+.
4+.5
4+.5
4+.5
4+
4+.5
4
1,.,,am
45./
45.+
45.+
4-.
4-.
4-.:
4-.+
,
11.,,am
45.
45.-
45.-
4-.1
4-.1
4:
4-./
1
/
14.,,am
45.4
45.:
45.:
4-.1
4-.1
4-./
4-.
4./
5
,1.,,pm 45.4
45./
45./
45.:
45.:
4-.4
4-.4
/
-
,4.,,pm 45.
45.:
45.:
4-.
4-.
4-.:
4-.+
-
:
,.,,pm 45.
45.:
45.-
4-.4
4-.4
4-.G
4-.G
G
G
,/.,,pm 45.4
45.G
45.-
4-.1
4-.1
4-.-
4-.G
/,.
+
,5.,,pm 45.1
45.5
45./
45.+
45.+
4-.
4-.
G.4
1,
,-.,,pm 45.1
45.5
45.
45.-
45.-
45.+
45.:
5.1
11
,:.,,pm 45
45./
45.4
45./
45./
45.-
45.5
1.5
14
,G.,,pm 45
45./
45.1
45.
45.
45.:
45.5
4G
1
,+.,,pm 45
45.
45.1
45.
45.
45.:
45./
4:.4
5.2 Ca&c&ati#' #$ !at r!
1.) @or first first heat heat echang echanger er Td1> nlet temperature of air > 45.G Td4> outlet temperature of air>45.4 $1> enthalpy of air at inlet>51.5 $4> enthalpy of air at outlet>5, $eat re'ected > h1h4 27
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Air cooler with Split Cooling Unit
>51.55, >1.5 #'C#g 4.) @or second second heat heat echang echanger er Td1>4-.1! Td4>45.h1>5,.4 h4> 5, heat re'ected > 5,.45, >,.4 K'C#g .) .) @or @or thir third d $E $E Td1>4-.G! Td4> 4-.h1>5.5 h4>54 heat re'ected > 5.5 54 >1.5 #'C#g
The geometric arrangement of heat echanger is as shown in fig. typically one fluid (air) moves over the tubes in cross flow while other fluid(water) at relatively lower temperature passes through tubes. The rows of tubes are staggered in direction of air flow. The configuration of tubes is characteri8ed by tube diameter % transverse pitch A 9. The flow condition across tube ban# is dominated by boundry layer separation effect and by wa#e interaction which influence convection heat transfer. Fa':
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There are two fans used in the modified system. ?ne in split unit and the other in the evaporative cooler .The function of the @an in %esert "ooler is to provide air with sufficiently high velocity to give desired air motion and effect to the human occupants.
Figr! 5.1 Fa' S"!ci$icati#' #$ Fa':
Ehaust @an<154./ mm 15,, rpm! 1 phase! / pole Electric type fan< 44,C4/,=! 5,$8! " Aower 1GW
Sb,!rsib&! P," :
The pump is used to circulate water through the pads of %esert.
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Figr! 5.2 P," S"!ci$icati#' #$ P,": Aower "onsumption< 1GW =oltage<" 44,= ?utlet Io88le &i8e<U Faimum $ead<1.5m (5 @t.) Faimum @low< :5, 9C$
Ta'=:
Tan# is used to hold sufficient 0uantities of water to enable the pump to "irculate the desired amount of cooling water. t is large enough to hold a good 0uantity of water. The capacity of tan# may range from G, to 14, litres. The water being circulated after every cycle falls falls bac# bac# in to the the tan# tan# and and cons consta tant nt circu circulat latio ion n is main maintai taine ned. d. s the the wate waterr goes goes on evaporating slowly and slowly the water content in the tan# goes on decreasing. $ence the tan# should be refilled with water after a definite 0uantity of time! which depends on the no. of hours of cooler use. Fore is the use! 0uic#er the tan# gets empty. The tan# is generally made of galvani8ed sheet metal but it is not at all compulsory to use this #ind. Even the cement tan#s can be used. drain valve should be necessarily present in the tan# so as to facilitate the cleaning and maintenance operations.
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Figr! 5.( 5 .( Ta'= Ta'=
The above figure 5. shows the actual picture of tan# used in the cooler. The si8e for the same is -G-,1G cm and the capacity is about G, litres. Pas:
The function of pads is to assists in the evaporation of water by capillary action and thus provides the cooling effect. The pads are fied in the body of %esert "ooler and eposed to the atmosphere on the outer side! so that the air #eeps on flowing through them. The pads in use today are generally spen Wood Aad! which are easily available with the cooler dealers. Jenerally three pads are used in the cooler. The pads under the action of dust and dirt particles lose their efficiency with use* hence they should be replaced every year. They are not very costly and cost around 5,1,, rupees per pad! depending on the 0uality.
the
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Figr! 5.3 C#c#'t C#ir Pa Ot!r B#+:
The outer body can be made from different materials depending on the cost and convenience. They can be either made of Wood or can be @abricated from sheet metal. Iow adays the the Alastic body cooler are also widely manufactured by some companies due to advantages li#e 9ow weight! corrosion free and easy maintenance.
Figr! 5.5 Ot!r B#+ #$ C##&!r Pi"i'g:
Their function is to carry the circulating water the pump and distribute the water evenly above all the pads to produce uniform cooling. The pipes used nowadays are of plastic so as to avoid corrosion and long life. $oles are provided in the pipes above the pads! so as to allow the water to fall over the pads from the holes. These holes should be regularly chec#ed to ensure a proper flow of water over the pads. f they get clotted under the action of dust and dirt ! they should be cleaned properly. lso the other piping is used for circulating the coolant through split unit. Fr#'t C#%!r:
The @ront "over present in front of the @an serves a no. of purposes. @irstly! they give a good and pleasing appearance to the cooler. &econdly! they act as a safety device! so as to #eep human organs away from the fan. The louvers present in the "over are also used to direct the flow in the desired direction.
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5.( I'str,!'tati#'
*!asri'g A""arats< Thermometer! THER*O*ETER
t!r,#,!t!r (from the Jree# (thermo) thermo) meaning VwarmV and meter ! Vto measureV) is a device that measures temperature measures temperature or or temperature temperature gradient gradient using a variety of different principles. thermometer has two important elements< the temperature sensor (e.g. the bulb on a mercury thermometer) in which some physical change occurs with temperature! plus some means of converting this physical change into a value (e.g. the scale on a mercury thermometer). Thermometers increasingly use electronic means to provide a digital display or input to a computer.
Figr! 5.6 T!r,#,!t!r
E'!rg+ *!t!r n electricity meter or energy meter is a device that measures the amount of electric of electric energy consumed energy consumed by a residence a residence!! business! business! or an electrically powered device. Electricity meters are typically calibrated in billing units! the most common one being the #ilowatt hour kWh kWhX. X. Aeriodic readings of electricity meters establishes billing cycles and energy used during a cycle.
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The energymeter is used to measure the energy consumed by each device individually for a specific time
5.3 EPERI*ENT PROCEDURES The following procedures will be as follows< a) The testing testing model model (air (air cooler) cooler) will will be observed observed steady operation. operation. b) Three calibrated thermometers will be located at the positions shown in setup to measure the temperatures i. t1= Wet bulb temp. of moist air ! ii. t4= temp. of supply air ! iii. iii. t > %ry %ry bulb bulb temp. temp. of of inlet inlet air air.. c) &imilarly tw4 wet bulb temp. will be measured d) The readings readings will be measured measured after every one hour e) This procedure procedure is is repeated repeated after after every every hour hour until until 1, pm. f) This eperim eperiment ent will will be repeated repeated for for three cooling cooling mediums! mediums! three three Fedias Fedias which which are available commercially. g) ?ur ?ur ob'e ob'ect ctiv ivee is to test testss the the cool cooler er on coco coconu nutt coir coir unde underr same same epe eperi rime ment ntal al procedure.
5.5 EPERI*ENTATION 34
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Air cooler with Split Cooling Unit
The below figures 5.G P 5.+ shows the actual set up of evaporative (%esert) cooler used for the testing purpose. ll the components used in the assembly of cooler are discussed in the previous point (5.4)
Figr! 5. Ass!,b&+ #$ D!s!rt c##&!r s! $#r t!sti'g
35
Modifed Air cooler with Split Cooling Unit
Figr! 5. S!t " #$ D!s!rt C##&!r s! $#r t!sti'g
CALCULATION 1./ Satrati Satrati#' #' E$$!ct E$$!cti%!'! i%!'!ss ss
η>1,,O (Td1Td4CTd1Twb) Where! Td1 > dry bulb temperature(° temperature( °")> /4 Td4 > outlet temperature(° temperature(°")> 45 Twb Twb > thermodynamic wet bulb temperature> te mperature> 1: η > saturation efficiency(% efficiency(%) η>1,,O (/445C/41:) η>4G7
2./ H!at tra's tra's$!r $!r C#!$$ C#!$$ici!' ici!'tt
0>hs∆ 0>hs∆T Where! h > heat transfer coefficient (W m4K 1)* s > total wetted surface area of rigid media (m4)* and 36
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ta#en to be the log mean temperature temperature difference difference for a constant constant ∆T is usually ta#en water temperature in the heat echanger! which is assumed to e0ual the wetbulb temperature. 0 > WCs where!
W> Aower consumption in watt 0 > $eat flu in wattC m4 0 >11C ,.,45+,G > 5,.5- wC m 4 h> 0Cs
∆T
h> 5,.5-C(,.,45+,G (/445))> 11/.:+5 11/.:+5
(W m4K 1)
(./ @rom Asychometric chart!
&r
%ry Bulb Temp.
Io
Wet Bulb Temp.
Enthalpy
K'CKg
2elative $umidity
(,")
(,")
1
/4
5
1,5
5,
4
45
1:
5,
5,
3./ "oefficient of Aerformance
"?A> Energy suppliedC Energy used "?A> ms. (h1 h4)C W Where! ms > Fass flow rate of air in KgCsec h1 > nitial Enthalpy of air in K'CKg h4 > @inal Enthalpy of air in K'CKg 37
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W> Aower consumption in watt "?A > ,.1--- (1,5 5,)C 11> : "?A > :
CHAPTER 6: RESULTS AND DISCUSSIONS 6.1 RESULTS RESULTS We have have got the results res ults as follows •
T! S"&it 'it ab&! t# ,ai'tai' t! t!,"!ratr! #$ "t# 25 °c s# it r!c!s t! t!,"!ratr! #$ air b+ 19 °c.
•
T! COP #$ t! s+st!, is 9.
•
T! t#ta& "#0!r c#'s,"ti#' #$ 'it is 1(> 0att
•
T! #!s '#t i'cr!as! t! ,iit+ #$ air
CHAPTER 9: CONCLUSION AND FUTURE SCOPE
The The epe eperi rime ment ntal al inve investi stiga gati tion on abov abovee conf confirm irmed ed that that spli splitt unit unit demo demons nstr trate ated d reasonable potential for use as a wetted media in evaporative cooling systems. "onse0uently! it creates the possibility of new sustainable engineering systems where either cooling or humidifyi humidifying ng is re0uired. re0uired. s the unit maintain the temperature 45 °c and it has low cost than " so it will be good replacement for ".. @or the future modifications! if the density of the split unit is reduced then we can achieve better performance than that achieved. lso we can increase the thic#ness of the pad to achieve good performance.
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REFERENCES 1) Dmprovement Dmprovement of evaporative evaporative cooling Efficiency Efficiency in Jreenhouses Jreenhouses by &irel#hatim &irel#hatim K. bbouda! and Emad . lmuhanna! nt. ; 9atest Trends gr. @ood &ci. =ol4 Io 4 ;une 4,14 2) M. ;. %ai! K. &mithy! DTheoretical study on a crossflow direct evaporative cooler using honeycomb honeycomb paper as pac#ing pac#ing material! Applied material! Applied Thermal Engineering !olume !olume 22 "ssue 1#! 1#! Septem$er 2%%2! 2%%2! &ages 1'1(1'#% #) Yhang iang ! 9iu Yhongbao! Mang Mang &huang! Fa ingbo! DThe Eperimental 2es earch ?n Two&tage Two&tage Water Evaporative "ooling &ystem ') 2. 2awang#ula* ;. Khedarib* ;. $irunlabha* B. Yeghmatic! DAerformance analysis of a new sustain sustainabl ablee evapor evaporati ative ve coolin cooling g pad made from from coconu coconutt coir! coir! "nternational *ournal of Sustaina$le Engineering Engineering !o !ol+ 1 ,o+ 2 *une 2%%- 11(.1#1 11(.1#1 /) Jhassem $eidarine'ad! Fo'taba Bo8orgmehr ! &hahram %elfani! ;afar Esmaeelian ; Eperimental investigation of twostage indirectCdirect evaporative cooling system in
various climatic conditions! 0uilding conditions! 0uilding and Environment Environment '' 2%%) 2%%) 2%(#.2%(+ 3) ;. Khedar Khedarii ! 2. 2awang 2awang#ul #ul!! W. "himch "himchave avee! e! ;. $irunl $irunlabh abh!! . Watanasu tanasungs ngsuit uit!! @easibility study of using agriculture waste as desiccant for air conditioning system!
4ene5a$le Energ6 Energ6 2- 2%%#) 131(.132-+ 131(.132-+ () 2. 2awang#ul! ;. Khedari! ;. $irunlabh and B.Yeghmati! DIew lternatives sing Iatural Faterials as %esiccant! -) $isham El%essou#y El%essou#y!! $isham $isham Ettouney Ettouney!! 'eel 'eel lYeefari lYeefari!! DAerformance DAerformance analysis analysis of twostage evaporative coolers! Chemical Engineering *ournal 1%2 2%%') 2//.233 . ) &$2E handboo# fundamentals. merican &ociety of $eating! 2efrigerating and ir"onditioning Engineers* 4,,5. 1%) %avis Energy Jroup. 1++. &F% ndirectC%irect Evaporative "ooler Fonitoring 2eport. Aro'ect report to the &acramento Funicipal tility %istrict. 39
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11) 11) ;.F. Wu! O. $uang! $. Yhang! DTheoretical analysis on heat and mass transfer in a direct direct evaporat evaporative ive cooler! cooler! Applied Thermal Engineering ! !olume lume 2 "ssues "ssues / 3 ! April 2%%! 2%%! &ages -%-'
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