| dc.description.abstract | Plate heat exchangers are widely used in industrial applications due to their excellent thermal performance, compact size, and high effectiveness. HFC-134a is one of the commonly used refrigerants in the market today. As a third-generation refrigerant that does not contain chlorine ions, it has an ozone depletion potential (ODP) of 0, thus posing no threat to the ozone layer. It is low in toxicity, non-flammable in air, and classified as safety category A1. Demonstrating good overall performance as a replacement for the previous generation refrigerant, CFC-12. HFC-134a is a high-pressure refrigerant suitable for low-temperature conditions, widely applied in refrigeration equipment such as refrigerators, automotive air conditioning, dehumidifiers, and chillers. With increasing environmental demands, the fourth-generation refrigerant HFO-1234yf has been developed to replace HFC-134a.
This study aims to understand the heat transfer and pressure drop characteristics of these refrigerants in a plate heat exchanger. Using HFC-134a and HFO-1234yf as working fluids, experiments were conducted on a plate heat exchanger with chevron angle of 65 degrees, maintaining a saturation temperature of 30°C. The study compares heat transfer coefficients and pressure drops at different refrigerant mass flow rates of G = 10, 20, and 30 kg/m2s.
The experimental results show that there is no significant difference in pressure drop between the two refrigerants. The heat transfer performance of HFC-134a is slightly higher, approximately 5% to 14% more than HFO-1234yf. Both refrigerants exhibit increasing heat transfer coefficients with higher quality. At low quality, nucleate boiling dominates the heat transfer mechanism, with heat transfer coefficients proportional to heat flux. | en_US |