상부 암모니아 사이클로 냉각되는 드라이아이스 제조 사이클의 성능 예측

Abstract

드라이아이스 제조 사이클의 효율적인 설계를 위하여, 이산화탄소 응축기를 상부 냉동 사이클로 냉각하여 압력을 낮추고 팽창밸브 입구의 과냉도릉 조절하고 상하부 각 2단 압축의 압력비를 조절하여 시뮬레이션을 시도하였다. 과냉도 조절을 위해 열교환기를 삽입하였으며, 설계된 사이클이 에너지의 합리적인 이용면에서 적절한지를 검정하기 위해 엑서지 해석을 병행하였다. 과냉도를 적절히 조절하고 이산화탄소 응축기압력과 상하부 각2단 압축의 중간압력을 조절함으로써 1 ton/hr 드라이아이스 생산 당 약 9㎾의 압축동력과 엑서지 손실을 줄일수 있었다. 엑서지 해석결과에 의하면, 하부 이산화탄소 아이클의 압축 단수는 증가되어야 하며, 상부 암모니아 사이클의 응축압력은 더 낮추어야 함을 알 수 있었다.

In order to reduce compression power and the exergy loss in a dry ice production cycle with cascade cooling, two heat exchangers were inserted in the cycle. Through simulation, the trends of compression power and irreversibility from the exergy analysis were examined in terms of two intermediate pressures, CO₂ condensing pressure, and degrees of subocooling in the inlets of expansion valves. About 9㎾ reduction in both compressionpower and exergy loss were found with the adoption of the subcooling by inserting heat exchangers as well as the pertinent choices of CO₂coodensing pressure and two intermediate pressures. Exergy analyis s suggests that the number of compressors in the bottorming CO₂cycle should be increased and the coodensing pressure in the topping ammonia cycle should be lowered for further improvenent.

In order to reduce compression power and the exergy loss in a dry ice production cycle with cascade cooling, two heat exchangers were inserted in the cycle. Through simulation, the trends of compression power and irreversibility from the exergy analysis were examined in terms of two intermediate pressures, CO₂ condensing pressure, and degrees of subocooling in the inlets of expansion valves. About 9㎾ reduction in both compressionpower and exergy loss were found with the adoption of the subcooling by inserting heat exchangers as well as the pertinent choices of CO₂coodensing pressure and two intermediate pressures. Exergy analyis s suggests that the number of compressors in the bottorming CO₂cycle should be increased and the coodensing pressure in the topping ammonia cycle should be lowered for further improvenent.