A Control Strategy for the Operation of a Reversible Heat-pump in Greenhouses

Reversible air to water heat pumps can be used to cool, heat, and dry greenhouse air. To handle the inherent complexity of the underlying system, a control strategy and apposite computer program were developed and tested. The control strategy is based on the concept of finite state automata. The control program was implemented and tested in a full size, real-time environment and has proven to be effective for the regulation of a reversible heat-pump/heat storage system in a greenhouse. The approach facilitates the addition of control logic and algorithms for the regulation of other environmental parameters such as CO2, light, irrigation, etc. A detailed description of the control algorithm as well as an example of its effect on heat-pump operation are given.