Development of switchless thin-plate sorption compressor and miniaturized check valves for 5 K J- T cooler

Abstract

The cell of the sorption compressor developed in this paper has a thin-plate shape to accelerate the pressure swing by reducing the heating and cooling periods. Its width, height and thickness are 100 mm, 100 mm and 4.6 mm, respectively. Two identical cells filled with 22.8 g of charcoal mass are operated alternately to generate and maintain significant pressure difference for the 5 K J-T cooler with the pre-cooling temperature of 15 K. The designed nominal pressure of the high-pressure and the low-pressure parts of the J-T cooler are 1000 kPa and 196 kPa, respectively. The mass flow rate and the pressure gradient of the thin-plate sorption compressor with commercial check valves are measured experimentally. As the performance of the compressor, COP of the compressor is estimated and compared with the compressor of previous researches. Furthermore, to reduce leakage rate and thermal inertia of check valves in the compressor, miniaturized check valve is specially designed and fabricated to replace the commercial valve. When the flow direction is reversed in the valve, the leakage is passively prevented by contacting two metal surfaces at low temperature (30 K). The essential parts of the valve are critically miniaturized to reduce the overall thermal inertia of the compressor system. The cracking pressure and the leakage rate of the developed check valve and the commercial check valve are measured to compare.