การออกแบบและพัฒนาระบบกักเก็บพลังงานความร้อนในรูปแบบน้ำแข็งสำหรับการปรับอากาศในโรงเรือน

Abstract

This research project was a conservation of energy in refrigeration system. The objective was to design and build a system to produce and store ice during night time and use it for air conditioning purpose during the day time. This system aimed to compliance with the electrical rate calculation of the real (time off use rate, TOU) instead of the tariff system, which rate of electricity during the night time was 67.1% cheaper than during the daytime and was 51.7% cheaper than usual rate. The ice thermal energy storage (ITES) sized 1.5 tons of refrigerating, using vapor compression refrigeration system. The compressor was 2.4 kW and condenser was 7.1 kW. The evaporator coil was designed to produce ice at 140 kg/day, equivalent to the performance of 13 kW. The Ø15.9 mm. copper pipes was used as an evaporator coil. The coil was connected to get her to form a parallel circuit in stalled in the stainless tank covered with 101.6 mm. thick polystyrene foam for insulation. The ice storage sized 320 liter. A 0.37 kW pump circulated the water in the tank to supply water through a evaporator coil at temperature of -12 °C to produce ice. The test was started by feeding water at 25 °C at a flow rate of 10.4 liter/second to produce the ice with refrigeration system. The refrigeration system was set to work for 5 hours with a measurement of power consumption and temperature of water every 20 minutes. Over time, the water temperature would be lowered to 0 °C, and then change to ice on the evaporator coil. During the day to the ice was then used for air conditioning in a greenhouse sized 2 x 3 x 3 m. The water was sprayed on to the ice to produce cold water at temperature of 0 - 0.5 °C. The cold water was then sent to the evaporative cooling system at flow rate of 0.38 liter/second. The evaporative cooling system used a 16 inches fan. From the experimental results showed Thermal energy storage system for use in the ice air conditioning in greenhouse. The capacity off ice is 130.214 kg/day. Temperature -3 ºC takes 3 hours to charge ice cold water to produce 178 liters of ice temperature 0 ºC to get her ITES system with latent heat energy in the form of ice is 12.3 kWh used. energy of 2.5 kWh, the coefficients of performance, COP of 3.0 and a cooling energy efficiency ratio (energy efficient ratio, EER) of 10.3 is bringing cold air in the greenhouse were tested for evaporative cooling. The results showed that the outside air with temperature of 23.1- 33.3 °C and a relative humidity of 53 percent was conditioned and the air temperature at the outlet of the evaporative cooling unit was 13.1 - 18.9 °C in average. The air temperature in the greenhouse was 15.1 - 20.4 ºC and the humidity in greenhouses in creased by 68.1 to 78.8%. temperature difference between inside and outside, on average 7.3 °C. The average rate of evaporative cooling unit was 7.1 kW. The electrical energy consumption was 0.37 kWh. The total air conditioning system energy consumption was 2.87 kWh. The coefficient of performance of the cooling system (system coefficients of performance, SCOP) is 2.5. The energy efficiency ratio (energy efficient ratio, EER) was 8.5. And the kW/TR was 1.3. The results of economic analysis showed that the ITES could reduce the cost of electricity by 36%. Keyword: Energy saving system, Refrigeration, thermal energy storage system, Ice on coil