STUDY THE COP AND THE EFFECT OF AIR FLOW FOR PILOT PLANT AIR REFRIGERATION UNIT

Abstract

An experiment was carried out to study the optimum condition of the parameters involved, which are air flow and coefficient of performance (COP) in order to increase the stability and efficiency of the refrigeration system for air conditioning unit (ACU) model. The instability of the refrigeration system may reduce the COP of the unit. The experiment was carried out in a lab scale, using R-134a as refrigerant with the maximum air throughput of 0.14 m3/s. The ACU consist of air conditioning system and refrigeration system. Air flow was calculated from the differential pressure (DP) at 15%, 30%, 45%, 60%, 75% and 90%. All readings were taken after 20 minutes in order to achieve steady state. The ambient and refrigerant temperature was recorded at all DPs. Other than that, the enthalpy at every point was calculated, to identify the COP and the compressor work produced. Ambient temperature at point 5 (AT5) showed steady increment, from 20.8°C to 24.7°C with increasing air flow. From the study, it found that there is a strong relationship between air flow and temperature where the higher air flow will increase the temperature, which is not efficient for the system. Therefore, air flow of 15% DP showed the best optimum condition for this refrigeration system, with the desired COP achieved. In daily life, it can be applied for the ACU in the car, where increase in air flow is not desirable for a long time, due to its efficiency (temperature increase).