PMF; rotary compressor; unitary air conditioner; non-bleed TXV
Unitary air conditioner in N.A. market takes the non-bleed TXV as its throttle valve. When the system turns off, the TXV automatically shut down to maintain the pressure in heat exchangers. This is benefit for SEER and comfort in use. However, pressure maintaining resulted in a fast-restart issue to fix-speed rotary compressor applying in this kind of system. To solve this problem, this paper firstly gave two concepts and principles of passive pressure balance and active pressure balance to conclude the means to achieve pressure balance in rotary compressor. Then, designed the technical scheme of PMF (Pressure Maintaining and Fast-restart) solution and analyzed the working process based on the two pressure balance principles. Furthermore, verified the PMF solution by compressor and system performance tests, PMF function test and reliability test. The results show that rotary compressor with PMF solution has good performance, stable PMF function and high reliability, which is a suitable product for unitary air conditioners.