Analysis of supermarket CO2 refrigeration cycles equipped with multi-ejectors
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This thesis presents an analysis of operating conditions in a refrigeration system locatedin supermarket Rema 1000 Prinsensgata, Trondheim (Norway). The main emphasis is put on aproblem with oversized gas cooler, which occurs during low ambient temperatures (in winter),and is a root of unstable operation of the whole system. Furthermore, possible solutions to this problem are depicted, among them are: division and cut-down of gas cooler s surface,application of bypassing valve to the gas cooler, triggering fresh air inside supermarket s airhandling-unit (AHU), and utilization of air shutters to the gas cooler. Subsequently, a simulation in a heat exchanger modelling computer program hXSIM (the Heat Exchanger Simulator) of the gas cooler split and increased subcooling is depicted. Lastly, the thesis portrays practical changes which were implemented in the system: exploitation of heat recovery system by snowmelting- unit (street-heating-unit), use of a shut-off valve to decrease the capacity of the gas cooler, implementation of a new controller for the ejectors, reprogramming fans, and also connection of the data acquisition system with energy meters mounted in supermarket s machine room.