Water Jet Nozzle to reduce the operation cost in Air Conditioning unit By The Group of Energy Conservation Team of The Faculty of Technology Industry of Mechanical Engineering Department of the University of Catholic Atma Jaya Jakarta For ASEAN Energy Efficiency and Conservation (EE&C) ASEAN Energy Awards 2006 Category: Special Submission 23~24 May 2006 1
Submission Form ASEAN Energy Efficiency and Conservation (EE&C) ASEAN Energy Awards 2006 CATEGORY: Special Submission 23 ~ 24 of May, 2006 2
COVERING NOTE FROM THE CLIENT AND ENGINEERS Group of Energy conservation team of the University of Catholic Atma Jaya Jakarta at Mechanical Engineering Department was developed a water jet nozzle installed in the condenser coil of the residential Air Conditioning units to reduce the power consumption of the electricity by 22% and increase the cooling capacity by 5%. This water jet nozzle can be installed in any residential Air Conditioning unit in a minute and gives an instant solution of energy conservation of the existing unit to reduce the rapid increase demand of the electricity in developing country such as Indonesia. The Group of Energy Conservation team of the University of Catholic Atma Jaya Jakarta at the Mechanical Engineering Department hereby agreed to allow the ACE Board of Judges and the Japanese experts to visit and verity the authenticity of the data. The Undersigned certified that the information given is true and accurate and prepared with the consent of the party/ies involved. The Head of Mechanical Engineering Department Of the University of Catholic Atma Jaya Jakarta Endorsed by Focal Point Ir. Isdarsanto Iskandar M.Sc Ms. Mariam Ayuni 3
Water Jet Nozzle to reduce the operation cost in Air Conditioning unit I. Introduction: The demand of the electricity in Indonesia increase rapidly, it is beyond the control of Indonesia government. Supply and demand ratio is shorted especially during the peak hours (18:00 22:00). This condition is getting worst and worst because people get used to the office environment (air conditioned environment), when they go back home they would like to have the same condition like the one in the office, therefore they have to install Air Conditioning units in their house. As we already know the consumption of electricity for Air Conditioning units is much bigger compare to the other home appliances such as TV, Radio, VCR, Refrigerator etc. It is a big challenge for the group of energy conservation team of Mechanical Engineering Department of the University of Catholic Atma Jaya Jakarta to help Indonesia government to solve the serious situation as soon as possible. The water jet nozzle installed in the condenser coil of the residential air conditioning unit to spray water during the high pressure of the condenser and off the spray during the low pressure of the condenser can reduce the operation cost of the electricity by 22% and increase the cooling capacity by 5%. II. System of Air Conditioning units: The Air conditioning system can be divided into 2 systems; a. Air Cooled system, b. Water Cooled system. Most of the residential air conditioning units belong to Air Cooled system. Table 1 shows the comparison of those two systems. The big difference of those two systems is in their COP (Coefficient of the Performance), for air cooled system, the theoretical COP is 4.28 whereas for water cooled system the theoretical COP is 6.67 which mean 55.8% more efficient compare to the air cooled system or the power consumption of the water cooled system is 55.8% less than the air cooled system. (If the power consumption of air cooled system is 1000 Watt, the power consumption of water cooled system needs only 641.8 Watt to have the same cooling capacity). The reason of this big difference in power consumption is due to the condensing pressure/temperature of those two system, the water cooled system has the condensing pressure/temperature of 1.4601MPa~1.6096MPa/38 o C~42 o C whereas air cooled system has 1.855MPa ~ 2.1227MPa/48 o C ~ 54 o C. If we can reduce the condensing pressure or temperature, the power consumption of that system will also reduce. 4
Air Cooled system Water cooled system Temperature in Condenser -Pressure in condenser Condenser (R22) -Temperature in Evaporator 48 C ~ 54 C 38 C ~ 42 C 1.855MPa~2.127MPa 1.4601MPa~1.6096MPa 4 C 4 C -COP 4.28 6.67 -Ratio of COP 44% 100% Table 1 Pressure (MPa) P2,3 P2,3 3 3 2 2 4 4 1 Figure 1 h3,4 h3,4 h1 h2 h2 Enthalpy (KJ/Kg) Enthalpy and pressure diagram of air conditioning unit The above Enthalpy and pressure diagram shows the difference between air cooled and water cooled air conditioning system. The process of Air Cooled Air conditioning system is 1-2-3-4-1 whereas water cooled air conditioning system is 1-2 -3-4 -1 5
Process : 1-2 or 1-2 is the process of compression of refrigerant from compressor. 2-3 or 2-3 is the process of condensation of vapor refrigerant from condenser. 3-4 or 3-4 is the adiabatic expansion of liquid refrigerant in expansion valve of capillary tube. 4-1 or 4-1 is the evaporation of liquid refrigerant in the evaporator. The energy needed to compress the vapor refrigerant in the compressor in the air cooled system is bigger than the water cooled system and the summaries of the whole process can be shown in table 1 and 2. System Temperature (Celsius) Liquid pressure (MPa) Gas Pressure (MPa) Location - 4 204.71 406.50 Evaporator Air Cooled 48 260.47 417.27 System 54 268.89 417.63 Water Cooled 38 247.00 415.91 System 42 252.32 416.55 Condenser Condenser Table 2 COP = Coefficient of Performance. h1 h4 h1- h4 COP = -------------- (air cooled); -------------- (water cooled) h2 h1 h2 h1 h2 h1 or h2 -h1 = The power consumption of the compressor. h1 h4 or h1-h4 = The cooling capacity of the evaporator. h2 h3 or h2 -h3 = Heat rejection in Condenser Table1 shows that the COP of water cooled system (6.67) is much higher than the air cooled system (4.28), it is 56% more efficient than the air cooled and also the cooling capacity of water cooled air conditioning unit will be bigger than the air cooled because h1 h4 > h1 h4. If we can change the air cooled air conditioning system having a similar or approaching the water cooled air conditioning system by changing the condensing temperature or pressure, then we can reduce the energy consumption of the air cooled air conditioning 6
system at the same time increase a bit the cooling capacity (see figure 1 the h1-h4 and h1- h4 ). This idea inspires the concept of installing water nozzle in air cooled air conditioning unit in the residential usage. III. Schematic Diagram of the Equipment and tested unit: Water nozzle jet Temperature sensor location Water Nozzle jet Condensing unit and water Nozzle jet 7
Indoor Unit Solenoid valve control unit Specification: -Cooling capacity : 13.500 BTU/h (3.958kW) -Type Compressor : Hermetically rotary compressor -Refrigerant : R-22 Unit Evaporator: - Number of rows : 2 - Face Area : 0.12m 2 - Fin per inch : 19 - Air Flow : 325CFM (522.5CMH) Condenser: - Number of row : 1 - Face Area : 0.4131 m 2 - Fin per inch : 19 - Air Flow : 550 CFM IV. Test Result As it is predicted theoretically that the power consumption will reduce and the cooling capacity will increase if we install a water jet nozzle. Table 3 shows the measurement of the compressor current (A), the suction (low) pressure, discharge (high) 8
pressure (psig), the temperature of the air in and out of the outdoor unit and the duration of the opening solenoid valve from start to off of the water jet with the flow rate of 0.7 L/minute. The indoor air temperature is also being measured simultaneously. It is clearly shown that if the water nozzle is running, the compressor current is average 22% less than the compressor current without water nozzle (as predicted theoretically). The same conditions apply to the suction and discharge pressure. Since the current of the compressor is directly related with the power consumption, therefore by reducing the current of the compressor by 22%, the power input of the electricity will also reduce by 22%. The air temperature coming out from the evaporator in the indoor unit is also down by 1.1~1.4 C. WATER NOZZLE flow rate = 0.7 l/minute NO OUTDOOR Air Temperature C Table 3 INDOOR Air Temperature C Current in Pressure in psig t Compressor (A) Low High In Out s In Out Water jet 1 3.98(122%) 42 240 28 38 23 19.6 START ON 3.26 (100%) 31 190 28 32 1'44 23 18.2 OFF 2 3.81(121%) 40 230 28 37 23 19.3 START ON 3.16(100%) 30 185 28 31 2'16 23 18.1 OFF 3 3.76(123%) 40 230 28 37 23 18.7 START ON 3.06(100%) 30 180 28 31 3'06 23 17.6 OFF This means the cooling capacity of the indoor unit is also increase by approximately 5% when the water nozzle jet is on (as predicted theoretically). The on and off of the solenoid valve which controls the water flow is done automatically by temperature controller. This temperature controller gets some signal from the temperature sensor which is installed in the condenser coil. This temperature sensor will sense the condenser temperature and transmitted to the on/off temperature controller inside the solenoid valve control unit to operate the solenoid valve, so that the operation of this water jet nozzle will be controlled automatically. 9
CURRENT & POWER INPUT AIR CONDITIONING WITH/WITHOUT WATER JET NOZZLE Current (Ampere) 5 4 3 2 1 With Water Jet Nozzle Without Water Jet Nozzle Power Input (Watt) 1200 1000 800 600 400 200 10 20 30 40 50 60 70 Time (Minute) Figure 2 Figure 2 shows us the comparison of the current and power input between the air cooled residential air conditioning unit with and without water jet nozzle. Even though the reduction of the energy consumption is not as big as using water cooled air conditioning units (56%) however by reduction the power consumption by 22% is significant and in addition to that there is an increase in cooling capacity by 5% and the Break Even Point (BEP) of installing this unit is also less than 12 months. V. Conclusion: The water jet nozzle installed in the condenser coil is a simple and straight forward solution to reduce the power consumption of the residential air conditioning unit by 22% and also can increase the cooling capacity of the unit by 5%. This water jet nozzle can be considered as one of instant solutions for the country who suffers from the scarcity of the electricity due to the increase of the residential air conditioning usage. The only side back of this water jet nozzle is that we still need about 0.7 L/minute of water to do this job, as we know in some countries, they are not only scarcity of the electricity but also they are scarcity of the water. 10