Inverse cycles modeling without refrigerant property specification

A method is presented and tested which, implemented along with a lumped dynamical model of an inverse cycle, allows for the description of the system with very simple mathematical tools, without any need to possess information about the thermophysical properties of the refrigerant fluid operating in the cycle. The algorithm, based on the fluid independent Carnot cycle, is applied both to a household refrigerator and to a direct expansion, variable capacity, solar assisted heat pump (DX-SAHP). The validity of the approach is established by comparing the numerical results of the proposed simplified approach to transient and time averaged data based on consolidated thermodynamic-cycle- simulators which make use of full standard fluid properties description. Simulations comparisons confirm the ability of the proposed model to closely adhere to the dynamic behavior of the considered devices and disclose the opportunity to develop inverse-cycle-models so simple to be easily embedded, along with their sensitivity features, in cheap model-based regulators and transient control strategy developments.