Method for controlling a vapour compression system

摘要

A method for controlling a vapor compression system, such as a refrigeration system, preferably an air condition system, comprising at least two evaporators. While monitoring a superheat (SH) at a common outlet for the evaporators, the amount of available refrigerant is controlled in response to the SH and in order to obtain an optimum SH value. The available refrigerant is distributed among the evaporators in accordance with a distribution key. The distribution key is preferably obtained while taking individual consideration to operating conditions for each of the evaporators into account. Thereby the vapor compression system can be operated in such a way that each of the evaporators is operated in an optimal manner, and in such a way that the system in general is operated in an optimal manner.

主权项

1. A method for controlling a vapor compression system, the vapor compression system comprising a compressor, a condenser, at least two evaporators fluidly connected in parallel between the compressor and an expansion device comprising a multi-valve connected to each of the evaporators for controlling a flow of refrigerant across each of the evaporators, the at least two evaporators sharing a common outlet fluidly connected to the compressor, the method comprising the steps of:
monitoring a superheat, SH, only at the common outlet of the at least two evaporators; controlling an amount of available refrigerant in response to the monitored superheat, SH, at the common outlet of the at least two evaporators; and operating the expansion device to provide a superheat, SH, level which is sufficiently high to prevent liquid refrigerant from passing through the evaporators; obtaining a first distribution key determining the relative allocation of available refrigerant among each of the evaporators, while the superheat, SH, level is sufficiently high to prevent liquid refrigerant from passing through the evaporators; adjusting the relative allocation of available refrigerant through each of the evaporators to be in accordance with the first distribution key; operating the expansion device to lower the superheat, SH, level, by increasing opening time of the expansion device or by decreasing the refrigeration load on the vapor compression system; obtaining a second distribution key at the lowered SH level obtained by said operation of the expansion device, the second distribution key modifying the first distribution key's relative allocation of available refrigerant among each of the evaporators for the lowered SH level; and distributing the available refrigerant among each of the evaporators in accordance with the second distribution key's relative allocation of available refrigerant by using the expansion device.