Cooling Tower

ABSTRACTThe objectives of the cooling tower experiment are to determine the correlation of water to air mass flow ratio with increasing water flow rate and to determine the cooling load effect, the effect of different flow rates on the wet bulb approach. Another objective is to estimate the evaporation rate of water (water loss) for the tower. The experiment is varied by using three variables; heating load, blower damper and water flow rate. The experiment is started by undergoing general start-up procedure. Valves 1 to 6 are closed, while valve 7 is partially opened. The load and make-up tank is filled with de-ionised water. Installation of cooling tower is done appropriately. The water flow rate is set to 2.0 LPM, heating load 1.0 kW and fully opened the damper. The differential pressure sensor is also checked. The unit is left to operate for 20 minutes to achieve standard steady state operations. Water level in make-up tank is observed and refilled if it decreased. The first experiment is started by varying the heating load. The variables are 0.5 kW, 1.0 kW and 1.5 kW. Water flow rate and blower damper is fixed to 2.0 LPM and fully opened respectively. The efficiencies of cooling tower by using 0.5 kW, 1.0 kW and 1.5 kW are 113%, 95 %, 87 % respectively and their mass flow rate per area are 1.697 10-3kg/m2s, 1.698 10-3kg/m2s and 1.698 10-3kg/m2s respectively. In second experiments, the air flow is varied by fully-open the blower (100 % air flow) and half-open the blower (50 % air flow). The heating load and the water flow rate are fixed to 0.5kW and 2.0 LPM respectively. Its efficiencies are 86 % and 86 % respectively while the mass flow rate per area are 1.698 10-3kg/m2s and 1.698 10-3kg/m2s respectively. The third experiment is done in order to determine the effects of water flow rate. Thus, the water flow rate is varied to 2.0 LPM, 2.4 LPM and 2.8 LPM. The heating load and blower damper are fixed to 0.5 kW and fully-open respectively. The efficiencies of the cooling tower are 100 %, 106 % and 111 % respectively. The mass flow rates per area are 1.692 10-3kg/m2s, 2.033 10-3kg/m2s and 2.375 10-3kg/m2s respectively.

INTRODUCTIONThe laboratory cooling tower is a cooling tower unit from a commercial air conditioning system used to study the principles of cooling tower operation. It is used in conjunction with a residential size water heater to simulate a cooling tower used to provide cool water to an industrial process. In the case of the laboratory unit, the industrial process load is provided by the water heater. The laboratory cooling tower allows for complete control of the speed of the fan used in cooling the warm return water and the pump used to return the cooled water to the water heater. Experiments can be conducted which study how adjustment of one or both of these parameters affects the amount of heat removed from the water provided to the water heater.Cooling towers are heat transfer devices used to remove process waste heat to the atmosphere. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or rely solely on air to cool the working fluid to near the dry-bulb air temperature. Common applications include cooling the circulating water used in oil refineries, chemical plants, and building cooling. The towers vary in size from small roof-top units to very large hyperboloid that can be up to 200 meters tall and 100 meters in diameter, or rectangular structures that can be over 40 meters tall and 80 meters long. Smaller towers are normally factory-built, while larger ones are constructed on site.The most widely used in the process industries for employing water by using re-circulated cooling water systems. In the cooling water systems, the processes involved are rejecting the heat from water by evaporation and remove process waste heat into the environment. The cost for this process is inexpensive and very dependable means of removing low grade heat from your process. Environmental considerations, by minimizing consumption of potable water, minimizing the generation and release of contaminated cooling water, and controlling the release into the environment of chemicals from leaking heat exchanger (HX), form the second major reason. It is used to provide lower than ambient water temperatures and are more cost effective and energy efficient than most other alternatives. Cooling towers are commonly used in many commercial and industrial processes, according to its classifying use.Cooling towers also can be categorized by its air-to-water flow. Crossflow is one of them. Crossflow is a design in which the air flow is directed perpendicular to the water flow (figure1). Air flow enters one or more vertical faces of the cooling tower to meet the fill material. Water flows (perpendicular to the air) through the fill by gravity. The air continues through the fill and thus past the water flow into an open plenum area. A distribution or hot water basin consisting of a deep pan with holes or nozzles in the bottom is utilized in a crossflow tower. Gravity distributes the water through the nozzles uniformly across the fill material.

Figure1. crossflow type design.The counterflow is another design for cooling tower. It is completely opposite to the above crossflow design. Air flow enters one or more vertical faces of the cooling tower to meet the fill material. Water flows (perpendicular to the air) through the fill by gravity. The air continues through the fill and thus past the water flow into an open plenum area. A distribution or hot water basin consisting of a deep pan with holes or nozzles in the bottom is utilized in a crossflow tower. Gravity distributes the water through the nozzles uniformly across the fill material.5Figure2. counterflow type design

OBJECTIVES To determine the correlation of water to air mass flow ratio with increasing water flow rate. To determine the cooling load effect. To know the effect of different flow rates on the wet bulb approach. To estimate the evaporation rate of water (water loss) for the tower.THEORYA cooling tower is a specialized heat exchanger that has been modified in which air and water are brought into direct contact for the transfer of heat to affect. To accomplish that, it is spraying a flowing mass of water by the spray-filled tower into a rain-like pattern, through which an upward moving mass flow of cool air is induced by the action of a fan. Cooling tower use the principle of evaporative or wet-bulb cooling in order to cool the water. It has some advantages over a conventional heat-exchanger such as it can achieve water temperatures below the temperature of the air used to cool it. Besides that, it is also smaller and cheaper for the same cooling load.Ignoring any negligible amount of sensible heat exchange that may occur through the walls or casing of the tower, the heat gained by the air must equal to the heat lost by the water by equilibrium. Within the air stream, the rate of heat gain is identified by the expression G (h2 h1), where:

G = Mass flow of dry air through the towerlb/min. h1 = Enthalpy (total heat content) of entering airBtu/Ib of dry air. h2 = Enthalpy of leaving airBtu/Ib of dry air.

Within the water stream, the rate of heat loss would appear to be L (t1 t2), where:

L = Mass flow of water entering the towerlb/min. t1= Hot water temperature entering the towerF. t2 = Cold water temperature leaving the towerF.

This derives from the fact that a Btu (British thermal unit) is the amount of heat gain or loss necessary to change the temperature of 1 pound of water by 1F. However, because of the evaporation that takes place within the tower, the mass flow of water leaving the tower is less than that entering it, and a proper heat balance must account for this slight difference. Since the rate of evaporation must equal the rate of change in the humidity ratio (absolute humidity) of the air stream, the rate of heat loss represented by this change in humidity ratio can be expressed as

G (H2 - H1) (t2 - 32)where: H1 = Humidity ratio of entering airlb vapor/lb dry air. H2 = Humidity ratio of leaving airlb vapor/lb dry air.

The notation (t2 - 32) = An expression of water enthalpy at the cold water temperatureBtu/Ib. (The enthalpy of water is zero at 32F) Including this loss of heat through evaporation, the total heat balance between air and water, expressed as a differential equation, is:

G dh = L dt + G dH (t2 - 32) (1)

The expression L dt in equation (1) represents the heat load imposed on the tower by whatever process it is serving. However, because pounds of water per unit time are not easily measured, heat load is usually expressed as:

Heat Load = gpm x R x 813 = Btu/min. (2)where: gpm = Water flow rate through process and over towergal/min. R = Range = Difference between hot and cold water temperaturesF. 813 = Pounds per gallon of water.

Note from formula (2) that heat load establishes only a required temperature differential in the process water, and is unconcerned with the actual hot and cold water temperatures themselves. Therefore, the mere indication of a heat load is meaningless to the Application Engineer attempting to properly size a cooling tower. More information of a specific nature is required.

Optimum operation of a process usually occurs within a relatively narrow band of flow rates and cold water temperatures, which establishes two of the parameters required to size a cooling towernamely, gpm and cold water temperature. The heat load developed by the process establishes a third parameterhot water temperature coming to the tower. For example, lets assume that a process developing a heat load of 125,000 Btu/min performs best if supplied with 1,000 gpm of water at 85F.With a slight transformation of formula (2), we can determine the water temperature elevation through the process as:Therefore, the hot water temperature coming to the tower would be 85F + 15F = 100F.

Having determined that the cooling tower must be able to cool 1,000 gpm of water from 100F to 85F, what parameters of the entering air must be known? Equation (1) would identify enthalpy to be of prime concern, but air enthalpy is not something that is routinely measured and recorded at any geographic location. Wetbulb temperature is the only air parameter needed to properly size a cooling tower, and its relationship to other parameters is as shown in the Figure 1 diagram.

Figure 1

APPARATUS Water cooling tower MODEL: HE-152

EXPERIMENTAL PROCEDUREGeneral start-up procedure.

1. Valve V1 to V6 are ensured to be closed while valve V7 is partially closed.2. The load tank is filled with deionised water.3. The make-up tank is filled with deionised water up to zero mark on the scale.4. Deionised water is added to the wet bulb sensor reservoir to the fullest.5. The appropriate cooling tower is installed for the experiment.6. All appropriate tubing to the differential pressure sensor is connected.7. The temperature set point of temperature controller is set to 45C. The 1.0 kW water heaters is switched on and the water is heated up to approximately 40C.8. The pump is switched on and the control valve V1 is slowly opened. The water flow rate is set to 2.0 LPM. A steady operation where the water is distributed and flowing uniformly through the packing is obtained.9. The fan damper is fully opened and the fan is switched on. Check that the differential pressure sensor is giving the reading : a. To measure the differential pressure across the orifice, open valve V4 and V5 ; close valve V3 and V6.b. To measure the differential pressure across the column, open valve V3 and V6 ; close valve V4 and V5.10. The unit is being let to run for 20 minutes for the float valve to correctly adjust the level in the load tank. Refill the make-up tank as required.11. The unit is now ready to use.Experiment 1.1. The heater is switched on and set to 0.5 kW.2. Pump and blower is then been switched on.3. The blower damper is fully opened.4. The water flow rate is set to 2 LPM.5. The water cooling tower is being let to operate for 10 minutes.6. The reading is taken when the float valve is correctly adjusted.7. Step 1-6 is being repeated with 1.0 kW and 1.5 kW heating load.

Experiment 2.1. The heater is switched on and set to 0.5 kW.2. The blower damper is fully opened.3. Set the water flow rate to 2 LPM.4. The unit is being let to run for 10 minutes.5. The reading is taken after steady operation achieved.6. Step 1-5 is being repeated with half opened blower damper.Experiment 3.1. The heater is switched on and set to 0.5 kW.2. Pump and blower are switched on.3. The blower damper is fully opened.4. The water flow rate is set to 2 LPM.5. The unit is being let to operate for 10 minutes.6. The reading is taken after steady operation achieved.7. Step 1-6 is being repeated with 2.4 LPM and 2.8 LPM.General shut-down procedure.1. The heater is switched off to let the water to circulate through cooling tower for 3-5 minutes until the water is cooled down.2. The blower is switched off and the blower damper is fully closed.3. The pump and power supply is switched off.4. The water in the reservoir tank is retained.5. The water from the unit is completely drained off.

RESULTSDESCRIPTIONWATER FLOWRATE (LPM)

TOP

Air Outlet Dry Bulb, T325.024.824.5

Air Outlet Wet Bulb, T426.025.525.0

Water Inlet Temperature, T530.228.427.4

STATION III

Air Dry Bulb, T828.027.727.6

Air Inlet Wet Bulb, T927.327.227.1

Water Temperature, T1427.227.027.0

STATION II

Air Dry Bulb, T1027.327.226.9

Air Inlet Bulb, T1127.527.427.2


STATION I

Air Dry Bulb, T1227.627.527.4



BOTTOM

Air Inlet Dry Bulb, T128.028.127.8



Orifice Differential, Dp (Pa)958880

Water Flow rate, Ft (LPM)2.02.42.8

Heater Power, Q1442 W426 W425 W

DESCRIPTIONHEATER POWER

0.5 kW1.0 kW1.5 kW

Air Inlet Dry Bulb, T127.927.928.0


Air Outlet Dry Bulb, T324.025.026.2

Air Outlet Wet Bulb, T424.624.725.4

Water Inlet Temperature, T527.630.232.8

Water Outlet Temperature, T624.224.825.6

Orifice Differential, DP1 (Pa)696147

Water Flow Rate, FT1 (LPM)2.02.02.0

Heater Power,Q1 (W)4368201235

DESCRIPTIONAIR FLOW

100%50%

Packing density (m-1)110110

Air Inlet Dry Bulb, T127.928.0

Air Inlet Wet Bulb, T224.524.6

Air Outlet Dry Bulb, T325.825.4

Air Outlet Wet Bulb, T426.025.7

Water Inlet Temperature, T529.629.0

Water Outlet Temperature, T625.225.1

Orifice Differential, DP1 (Pa)3935

Water Flow Rate, FT1 (LPM)2.02.0

Heater Power,Q1 (W)442440

Pressure drop across packing DP2 (Pa)76

SAMPLE CALCULATIONCross sectional area : 225 cm2High : 60 cmPack column : 110 m-1

EXPERIMENT 1: EFFECT OF HEATING LOADFixed variables;1. Air flow = 100% (Damper fully open)2. Water flow rate = 2.0 LPMa) Heating load = 1.0 kWRange of cooling tower;Range = Water inlet temperature, T5 - water outlet temperature, T6= 30.2C 24.8C=5.4CApproach of cooling tower;Approach = Water outlet temperature, T6 Air outlet wet bulb, T2 = 24.8C 24.5 C = 0.3 CEfficiency of cooling towers; = 100 = 100 = 95 %Total cooling load;Cooling load = pump input, Q1 + heating load = 820 W + = 1820 W

Air mass flow rate per unit area;

From psychometric chart ( (Felder & Rousseau, 2005, p. 385); Air inlet wet bulb, T2 @ Twb = 24.5 CInterpolation:Twb (C) (m3/kg)

20.000.85

24.50

30.060.90

= 0.872 m3/kgCross-sectional Area of tank load = 225 cm2 = 0.0225 m2Thus; = = 1.698 10-3 kg/m2sWater mass flow rate per unit area;

From psychometric chart ( (Felder & Rousseau, 2005, p. 385); Air inlet wet bulb, T2 @ Twb = 24.5 CInterpolation:Twb (C)hr(kg water/kg air)

20.000.0286

24.50hr

30.060.0148

hr = 0.0224 kg water/kg air

= 0.0758 kg/m2s

Water mass flow rate per unit area;

r = 44.64Heating load (kW)0.5 1.01.5

Range (C)3.45.47.2

Approach of cooling water (C)-0.40.31.1

Efficiency of cooling water, (%)1139587

Total cooling load (W)93618202735

Air mass flow rate per unit area (kg/m2s)1.697 10-3 1.698 10-3 1.698 10-3

Water mass flow rate per unit area(kg/m2s)0.07860.07580.0758

Water mass flow rate to air mass flow rate ratio, r46.3244.6444.64

EXPERIMENT 2: BLOWER DAMPERFixed variables;1. Heating load = 0.5 kW2. Water flow rate = 2.0 LPMa) Air flow = 100 % (Blower fully open) Range of cooling tower;Range = Water inlet temperature, T5 - water outlet temperature, T6= 29.6 C 25.2 C= 4.4 CApproach of cooling tower;Approach = Water outlet temperature, T6 Air inlet wet bulb, T2 = 25.2 C 24.5C = 0.7 CEfficiency of cooling towers; = 100 = 100 = 86 %Total cooling load;Cooling load = pump input, Q1 + heating load = 442 W + = 942 WAir mass flow rate per unit area; From psychometric chart ( (Felder & Rousseau, 2005, p. 385); Air inlet wet bulb, T2 @ Twb = 24.5CInterpolation:Twb (C) (m3/kg)

20.000.85

24.5

30.060.90

= 0.827 m3/kg = = 1.698 10-3 kg/m2sWater mass flow rate per unit area;

From psychometric chart ( (Felder & Rousseau, 2005, p. 385);Air inlet wet bulb, T2 @ Twb = 24.5 CInterpolation:Twb (C)hr(kg water/kg air)

20.000.0286

24.50hr

30.060.0148


= 0.0758 kg/m2s Water mass flow rate to air mass flow rate ratio

r = 44.64

Air Flow 100%50%

Range (C)4.43.9

Approach of cooling water (C)0.70.5



Air mass flow rate per unit area (kg/m2s)1.698 10-3 1.697 10-3

Water mass flow rate per unit area(kg/m2s)0.0758 0.0786

Water mass flow rate to air mass flow rate ratio, r44.6446.32

EXPERIMENT 3: WATER FLOW RATEFixed variables;1. Heating load = 0.5 kW2. Air Flow = 100 % (Blower fully open) a) Water Flow Rate = 2.0 LPMRange of cooling tower;Range = Water inlet temperature, T5 - water outlet temperature, T6= 30.2 C 25.1 C=5.1CApproach of cooling tower;Approach = Water outlet temperature, T6 Air inlet wet bulb, T2 = 25.1C 25.1C = 0 C

Efficiency of cooling towers; = 100 = 100 = 100 %Total cooling load;Cooling load = pump input, Q1 + heating load = 442 W + = 942 W

Air mass flow rate per unit area; From psychometric chart ( (Felder & Rousseau, 2005, p. 385); Air inlet wet bulb, T2 @ Twb = 25.1 CInterpolation:Twb (C) (m3/kg)

20.000.85

25.1

30.060.90

0.875 m3/kg = = 1.692 10-3kg/m2sWater mass flow rate per unit area;

From psychometric chart ( (Felder & Rousseau, 2005, p. 385);Air inlet wet bulb, T2 @ Twb = 24.6 CInterpolation:Twb (C)hr(kg water/kg air)

20.000.0286

24.60hr

30.060.0148


= 0.0759 kg/m2sWater mass flow rate to air mass flow rate ratio

r = 44.86

Water Flow Rate (LPM)2.0 2.42.8

Range (C)5.13.73.0

Approach of cooling water (C)0-0.2-0.3



Air mass flow rate per unit area (kg/m2s)1.692 10-32.033 10-32.375 10-3

Water mass flow rate per unit area(kg/m2s)0.0759 0.09290.1072


SAMPLE ERROR CALCULATIONThere are some errors that present in the calculation of Efficiency of cooling water, (%) for experiment 1 and 3. EXPERIMENT 1 : EFFECT OF HEATING LOADHeating load (kW)0.5 1.01.5

Range (C)3.45.47.2

Approach of cooling water (C)-0.40.31.1



Air mass flow rate per unit area (kg/m2s)1.697 10-3 1.698 10-3 1.698 10-3

Water mass flow rate per unit area(kg/m2s)0.07860.07580.0758


The efficiency of cooling water for 0.5 kW heating load is supposed to be less than 100% like the rest of manipulated variable, 1.0 kW and 1.5 kW. However, = 100 = 3.4 x 100 3.4-0.4 = 113 %This is due to the temperature of approach cooling water having a negative value. It is supposed to be greater than 0 C.

EXPERIMENT 3: EFFECT OF WATER FLOW RATEWater Flow Rate (LPM)2.0 2.42.8

Range (C)5.13.73.0

Approach of cooling water (C)0-0.2-0.3



Air mass flow rate per unit area (kg/m2s)1.692 10-32.033 10-32.375 10-3

Water mass flow rate per unit area(kg/m2s)0.0759 0.09290.1072


Same with experiment 1, the efficiency of cooling water, (%) is greater than 100%. However for this experiment, the errors occur in the manipulated variable of flow rate 2.4 LPM and 2.8 LPM.For water flow rate of 2.4 LPM, = 100 = 3.7 x 100 3.7 0.2 = 106 %

For water flow rate of 2.8 LPM,

= 100 = 3.0 x 100 3.0 0.3 = 111 %

This is also due to the temperature of approach cooling water having a negative value. It is supposed to be greater than 0 C.

DISCUSSIONThe experiment that was carried out is called cooling tower experiment. Cooling tower is a device that rejects heat which removes the waste heat to the atmosphere to achieve the temperature needed. The type of heat rejection in a cooling tower is termed "evaporative" where it allows a small portion of the water being heated to evaporate then is condensed into a moving air stream to provide significant cooling to the rest of that water stream. The heat from the water stream transferred to the air stream raises the air's temperature and its relative humidity to 100%, and this air is discharged to the atmosphere. The objectives of the cooling tower experiment are to determine the correlation of water to air mass flow ratio with increasing water flow rate and to determine the cooling load effect, and the effect of different flow rates on the wet bulb approach. Another objective is to estimate the evaporation rate of water (water loss) for the tower. The experiment is varied by using three variables; heating load, blower damper and water flow rate.

The correlation of water to air mass flow ratio is called r, is important to know the portion transferred by evaporation. The higher the evaporation of water, the mass flow rate of the water will be reduced which is what we actually wanted. Once the water mass flow rate is reduced, the mass flow rate of air that enters the column packing remains the same. So, there is more air that can cool the water. Hence, the effectiveness of the water to be cooled will be higher. The r value will need to be lower as possible to achieve higher portion of water evaporated. For water flow rates of 2.0 LPM, 2.4 LPM and 2.8 LPM, the r values are 44.86, 45.70 and 45.14 respectively. We can see that the water flow rate affects the r value for which the higher the water flow rate produces higher r value. . Hence, the cooling effectiveness will be higher in water flow rate of 2.0 LPM. Other than that, cooling load also determine the performance of cooling tower. Cooling load is the rate at which heat is removed from the water. The higher the cooling load, the higher the heat removal from the water. Hence, the water will experience lower temperature which is actually that we wanted. However, the cooling load is different according to its parameters. For parameter of heating load, of 0.5 kW, 1.0 kW and 1.5 kW, the cooling loads are 936 W, 1820 W and 2735 W respectively. We can see that the higher the heating load, the higher the cooling load would be. This is because the heating load is actually the power of the pump that compresses the water to increase the temperature and also pressure of the water. The higher the heating load, the higher the evaporation rate of the water. Thus, the temperature difference of the evaporated water with the temperature of air in the cooling tower will bring to great heat removal from the evaporated water. For parameter of blowing damper, which are half opened and fully opened, the cooling loads are 940 W and 942 W respectively. We can come into a conclusion that when the area of the damper is larger, the cooling load will be increasing because when the area of damper blower is wide, more air will be entered the cooling tower hence will cooled the evaporated more effectively. So, the heat removes from the water will be rapid and increases the cooling load. For parameter of water flow rate, 2.0 LPM, 2.4 LPM and 2.8 LPM, the cooling loads are 942 W, 926 W and 925 W respectively. Notice that, the higher the water flow rate, the lower the cooling load. This is due to the amount of water flows in certain time is in small portion. So, it makes it easier for the water to be evaporated and also removes heat to the atmosphere to achieve a lower temperature thus increase the cooling load.

In addition, approach is another term that used in cooling tower that tells how closely the leaving cold water temperature approaches the entering air wet bulb temperature. To be exact it is actually the temperature differences between the water leaving the cooling tower and the ambient wet-bulb temperature. Approach is the most important indicator of cooling water performance because it dictates the theoretical limit of the leaving cold water temperature and no matter the size of the cooling tower, range or heat load, it is not possible to cool the water below the wet bulb temperature of air. Hence, the leaving water temperature must be higher than the wet bulb temperature. The different air flow rates will affect the approach of the experiment. In this experiment, when the blower damper is opened fully, the air mass flow rate is 1.698 10-3 kg/m2s while when the blower damper is half-opened , the air mass flow rate is 1.697 10-3 kg/m2s. The higher the air mass flow rate, the higher the approach would be because the air that enters through the blower will decrease the wet bulb temperature so that the water leaving the tower will be higher than the wet bulb temperature. Furthermore, during the experiment there are some errors that occurred. The error is that we did not take the amount of water loss from the make-up tank every time the variables are changed. So, the errors affected the results of our experiment. The first error that occurs is that we cannot estimate the evaporation rate of water (water loss) for the tower. Other than that, the errors that occur is that efficiency of the cooling tower in the variable of heating load where for 0.5 kW, the efficiency is 113% which is more than 100%. For the variable of water flow rate 2.4 LPM and 2.8 LPM, their efficiencies are 106% and 111% respectively which are also more than 100%. This is probably due to the lower air mass flow rate that enters through the blower that makes the wet bulb temperature is higher than the leaving water temperature. So, the approach temperatures have a negative value. Notice that, all of the efficiencies that are more than 100% have a negative approach temperature value.

CONCLUSIONFrom the experiment that has been conducted we can conclude that, all objective of this experiment is achieved. The correlation of water to air mass flow ratio with increasing water flow rate has been determined. Where for water flow rates of 2.0 LPM, 2.4 LPM and 2.8 LPM, the r values are 44.86, 45.70 and 45.14 respectively. We also manage to calculate the effectiveness of cooling tower which is the highest at 2.0 LPM for 100%. The effect of heating load to the cooling tower is also achieved. The higher the amount of heating load, the more effective is the cooling tower performance. Other than that, cooling tower with fully opened blower will operate more effective compared with cooling tower with half fully opened. This experiment was not conducted successfully as there are errors when conducting the experiment. RECOMMENDATIONS The time required before all the reading is taken should be 25 to 30 minutes to make sure the operation is steady and stable. Make sure all the bulbs are fully with water so that it will not affect the experiment. Every experiment should be done in 3 times and record all the reading before calculate the average reading. We should wait about 30 minutes before starting every new experiment to ensure that the equipment in the stable condition. Auxiliary heater should be used during this experiment in order to increase the temperature difference between the cool supply water and the return water. This will allow the larger enthalpy difference. Do not put hands or something at any rotation equipment like fan or blower to avoid from any error in reading and experiment. Do not touch any electrical connection and turn off electric main immediately if there is any equipment malfunctions. Lab coats, goggles and safety helmet must be wearing before doing the experiment.

REFERENCES1. (2006). Retrieved May 29, 2012, from Chemical Engineer : http://chem.engr.utc.edu/webres/435F/3T-CT/3T-CT.html2. Applications of Cooling Tower. (n.d.). Retrieved May 29, 2012, from http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=57479193. Cengel, Y. A., & Boles, M. A. (2007). Thermodynamics, An Engineering Approach. Singapore: McGraw-Hill Education.4. Cooling Tower. (2011, January 5). Retrieved May 29, 2012, from http://www.cti.org/whatis/coolingtowerdetail.shtml5. Cooling Towers. (n.d.). Retrieved May 29, 2012, from Hydrosense: http://www.hydrosense.biz/index.php/sectors/cooling-towers/?gclid=CMXGq5bhia8CFUx76wodJg-JMg6. Felder, R. M., & Rousseau, R. W. (2005). Elementary Principles of Chemical Processes. United States of America: John Wiley & Sons, Inc.7. Norman, W.S; Absorption, Distillation and Cooling Towers (Longman, London, 1961)

APPENDICES

Figure 2 : Psichometric Chart

1

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Cooling Tower

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