Kazushige Kasai

Performance Evaluation and Optimization of a Refrigerant Distributor for Air Conditioner

Refrigerant mal-distribution in a distributor located at the inlet of the heat exchanger used for air conditioning systems plays an important role in the heat exchanger performance. The distribution performance at the distributor is greatly affected by flow conditions as well as geometrical parameters of the distributor. To clarify the distribution characteristics, it is essential to know flow rates of both liquid and vapor state at every branch tube after distribution. In other word, the information of the quality and the flow rate at the every branch tube are required. Acquiring this information, however, requires quite complicate experimental setup so far. This paper proposes a quite simple test method, however, allowing to obtain the value of quality and the flow rate of the refrigerant at the every branch tube of the distributor by measuring pressure drop and heat transfer rate of the branch tubes after distribution. By using the proposed evaluation method, the optimization for the geometrical parameters of the distributor was conducted to reduce the refrigerant mal-distribution and an optimized distributor is suggested. It is confirmed that the optimized distributor greatly reduces the mal-distribution of the refrigerant over the every branch tube regardless of the flow conditions. Meanwhile, by the flow visualization in the distributor, it is observed that certain amount of liquid refrigerant is stayed and swaying unstably at the bottom of the distributor. It is supposed that the liquid refrigerant behavior in the distributor great affects the distribution performance.Copyright