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Tests were conducted with a laminate evaporator for an automotive application. The tests were conducted with HFO-1234yf as the working fluid on an AC system bench. A laminate evaporator from MY 2008 medium sized sedan was used for this investigation. Tests were first conducted with R-134a and were then repeated by maintaining each test condition by changing the working fluid from R-134a to HFO-1234yf. Charge determination tests were also conducted with the new refrigerant. The refrigerant was used as “drop-in” refrigerant in the existing system. All original OEM parts were used with the alternate refrigerant. Same TXV set-point and lubricant type and quantity was used with HFO-1234yf. The new refrigerant has advantages due to the refrigerant thermodynamic properties that helps reduce the pressure ratio. Detailed test results have been presented in this paper.

A number of experiments were conducted to determine oil accumulation rates for a single tank laminate evaporator with the tank at the top. The tank at the top results in a U-shaped evaporator plate design at the bottom where oil can collect under extreme operating conditions. A typical 4 pass laminate evaporator was used for testing. R-134a with an oil circulation ratio of 3% was used for this study. The AC system was run for extended periods (2∼4 hours) at different compressor speeds to simulate the variation of load on the evaporator. Evaporator samples were taken off from the test stand and weighed after recovering refrigerant. The evaporators were designed such that it could be isolated by shutting off valves at the inlet and the outlet connections.