Experimental Study On Performance Of The Fan Coil Under Medium And Low-temperature Conditions

The development of food preservation industry which made the refrigerated environment of high-temperature have been widely applied. Generally, the suitable storage environment of various agricultural products including fruits and vegetables requires 8-20 ?. Optimizing and improving the performance of refrigeration equipment environmental chamber is significant for promoting the use of the high-temperature's refrigeration equipment environmental chamber. In practical refrigerated environment of high-temperature, which staffs frequently operate, the refrigerant terminal equipment (such as a cooling fan) connected with operating space for the personnel directly. That leads to a large amount of the refrigerant charge, and will inevitably result in a threat to the safety of staff. Using the system of secondary refrigerant can reduce refrigerant charge and avoid security risks. Fan coil is a common heat transfer equipment of secondary refrigerant in air-conditioning system, with low prices and many other advantages. If the fan coil used in the refrigerated environment of high-temperature, it would be bound to expand range of fan coil's use, while also addressing end equipment shortages of the refrigerated environment of high-temperature. Be different from the air conditioning system, the fan coil using in the refrigerated environment of high-temperature is under low temperature conditions, which deviates from the standard conditions of fan coil. Therefore, this article will focus on the studying changes of fan coil's cooling ability, the heat transfer performance and the wet factor analysis under low-temperature condition, and carry out theoretical analysis and experimental research of fan coil, which is used in the refrigerated environment of high-temperature.This topic establish mathematical model of the variable condition of cryogenic fan coil, through studying on fan coil air heat and moisture processes under wet and dry condition, and compared with a bench of fan-coil system which is established under the low temperature conditions. The paper analyzed the variation cooling capability, enthalpy efficiency, temperature difference and dehumidifying coefficient of the fan coil by changing the inlet temperature, flows of secondary refrigerant and environmental chamber temperature. Master changes of performance of fan coil under low temperature conditions.The results show that the cooling capacity of fan coil changing with the inlet temperature of secondary refrigerant is substantially linear. Compared with the standard conditions, cooling capacity is about 47.8%?8.7% of standard working condition under 18 ? condition; cooling capacity is about 41.2%?15.9% of standard working condition under 15 ? condition; cooling capacity is about 32.8%-11.9% of standard working condition under 12? condition; Maintain environmental chamber at constant temperature, constant refrigerant flow rate and air volume, inlet temperature of secondary refrigerant rise every 1 ?, the cooling capacity decrease by about 5%; Maintain inlet temperature of secondary refrigerant, at constant flow rate and air flow, environment chamber temperature stay at 18 ?,15 ?,12 ?, the cooling capacity in turn decreased by 12.9% and 9.41%; The enthalpy efficiency of fan coil has nothing to do with the inlet and outlet temperature of the secondary refrigerant and the inlet and outlet temperature of the air. But only related to the flow rate of the secondary refrigerant and the air volume. The proportion in the low temperature environmental chamber air cooling should be between 2.2-3.5. Appropriate chooses the inlet temperature of cold agent value is:environmental chamber temperature is 12 ?, the imported load cooling temperature is 4 ? and below; When the environment temperature is 15 ?, refrigerant inlet temperature should be chosen in between 4 ? and 7 ?; When the environment temperature is 18 ?, refrigerant inlet temperature should be chosen between 5 ? and 9 ?.Overall, the inlet temperature and the flow rate of the secondary refrigerant have a great influence on the fan coil. In order to facilitate project design and selection, based on experimental results, the paper fit practical engineering formulas of cooling capacity, temperature difference of inlet and outlet, temperature difference of heat transfer, enthalpy efficiency of full cooling capacity, enthalpy efficiency of sensible cooling capacity and dehumidifying coefficient, which deviate from standard conditions: Cooling capacity ;the temperature difference between import and export and the temperature difference of heat transfer:?tm=0.0511t2.3649twtwl-1.2496qv-0.1849 The correlation coefficient is 0.90 or more. Enthalpy efficiency of full cooling capacity: ?h=1.632Vy0.5191qm0.6114 and enthalpy efficiency of sensible cooling capacity: ?s=1.208Vy0.3135qm0.5951.The correlation coefficient is 0.95 or more.Dehumidifying coefficient: ?=0.7450t-0.3712twl0.5913qv0.1160. The correlation coefficient is 0.85 or more.