Experimental Modeling of Refrigerants at High Ambient Temperature
Abstract
High ambient temperature is well known to have an adverse impact on air conditioners; it lowers their cooling capacity along with their coefficient of performance. Moreover, air conditioning plays a significant role in damaging the environment as it contributes to both global warming and ozone depletion. In the past few decades, the Montreal agreement was introduced to protect the ozone layer from substances that contribute to its depletion. Developing countries are now facing the challenges of phasing out HCFCs such as R22 in the air conditioning sector. The aim of this study is to find an alternative refrigerant that can replace R22 after its phase out. The new refrigerant must have low environmental impacts and should be able to withstand operation in high ambient temperature countries. In this study, the hydrocarbon refrigerant R290 and the hydrofluorocarbon R410A were selected as alternatives. Furthermore, experimental testing was carried out on the baseline refrigerant R22 and R410A using a 7kW ducted split unit at three outdoor conditions: 35oC, 48oC, and 52oC. From the experimental results, a model based on R22 and R410A was developed using Engineering Equation Solver (EES). The model was successful in verifying the experimental results within a 15% error range, and was tested again with external data from (Eltalouny & Nielsen, 2016) [10]. After confirming its validity, the model was simulated to predict the performance of the alternative refrigerant R290 under the same experimental conditions and input data. To test the model’s validity on R290, results from (Eltalouny & Nielsen, 2016) were used. The model succeeded in predicting the COP and power consumption. The refrigerants demonstrated deterioration in their performance at elevated temperatures compared to their performance at a typical operating regime. With proper safety measures, and enhancement to the compressor efficiency, R290 can be considered as a promising alternative.
