Energy exchange refrigeration

In chemical plants, turboexpanders are used to produce refrigeration for cold box installations. In all except energy recovery applications, there are gas-to-gas heat exchangers downstream of the turboexpander. Figure 6-14 recaps a process flow diagram of a natural gas processing gas plant. 

The annual cycle energy system (ACES) has two basic components a very large insulated storage tank of water and a heating-only heat pump. The tank contains coils of pipe filled with brine (salt water) warmed by the water in the tank. The brine circulates through a heat exchanger and transfers its heat to the heat pump refrigerant. 

A refrigeration cycle to make ice from water with ammonia as the working fluid or energy carrier. Nearly 45% of the compression power is lost due to heat exchange in the evaporator and the condenser. 

In conclusion, the demonstration runs have shown that the membrane contactor dehumidification system is effective when the total loads of the refrigerated cell do not require an evaporative temperature of the cooling coil below —10 °C. In these conditions it has been shown that energy, operating costs and C02 emissions can be decreased up to 20% when optimized systems are built. The optimization is related mostly to the selection of adequate pumps, fans, heat exchangers. 

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