Experimental analysis of the performances of variable refrigerant flow systems

This paper presents a testing methodology applicable to variable refrigerant flow (VRF) equipment. A test bench is presented: it consists of a set of six calorimeters, each one fully instrumented and controlled in such a way to compensate almost all combinations of sensible, latent, heating and cooling loads. This test bench is used for a three-pipe VRF system with ve indoor units and one outdoor unit. Examples of testing results are presented in the paper, in order to illustrate the methodology and also validate a simulation model. The (heating or cooling) emission of each indoor unit is identi® ed thanks to a very accurate `air’ balance inside each calorimeter. Refrigerant side (pressure and temperature) measurements are used in order to identify the refrigerant flow rate and the characteristics of the compressors (isentropic effectiveness) and of the terminal units (heat transfer coef® cients) in different regimes. Examples of global performance evaluation are also presented in the paper.