This paper presents an establishment of a mathematical model to determine the optimal size of heat pipe (thermosyphon) heat exchanger for reduce the inlet air temperature in evaporative cooling system of greenhouse. The condition of a mathematical model is the total length of heat pipe is 1.5 m. A mathematical model will determine the optimal value of evaporator section and condenser section. The range of evaporator length is 0.5 – 1.4 m with an increment of 0.1 m and condenser length is in range of 0.1 – 1.0 m with an increment of 0.1 m. The inlet air temperature in evaporative cooling of greenhouse is depend on ambient temperature about 35 degree Celsius. While the cooling water temperature is 20 degree Celsius. Evaporative pad of evaporative cooling system is 2 m in width and 7 m in length. From the conditions above the optimize results from a mathematical model are as follows: evaporator section length is 0.9 m and condenser section length is 0.6 m moreover it was shown that investment net saving and maximum heat rate are 79.83 Thousand Baht 0.552 Million Baht and 15.6 kW respectively.

Here we present an experimental study of the single-effect adsorption cooling system using activated carbon-methanol working pair. The test unit was comprised of an adsorber a condenser and evaporator in vertical alignment. Heating and cooling of adsorber was mainly done by hot and cold water circulating through the water jacket. The evaporator and condenser was heated or cooled by flows of water through the internal coil. The adsorber was analyzed for its cooling rate when cooling was done by two approaches either cooling water and/or three thermosyphon heat pipes which both methods gave shortest cooling time. The investigated heat source and sink temperatures are; hot water temperature supplied to adsorber (70 80 90 oC) and cooling water temperature supplied to condenser (5 10 15 oC). An ultrasonic wave generator was attached to the bottom end of the evaporator to generate wave frequency varied by 8 10 and 14 kHz during evaporation phase. The ultrasonic wave can obviously reduce the evaporation time of methanol as well as to improve the system performance in terms of COP SCP and VCP. The system performance was considerably comparable to those from literatures. The highest COP and SCP obtained from this system was 0.718 and 248.90 W/kg respectively.