Transient state, Reciprocating compressor, Transient state
During development of refrigeration cycle simulations, the modelling of the compressor requires a trade-off between computational speed and level of detail. In that case, the use of semi-empirical models makes sense instead of complex 1-dimensional models which are common in the development phase of a compressor. Also the very low measuring effort for the adaption of these models favours their use. The present work contains a comparison of different semi-empirical models found in the literature which simulate the dynamic performance of reciprocating compressors. These models calculate the refrigerant mass flow rate and the compressor power based on polytropic compression and the formulation of a volumetric efficiency. The model parameters are determined by fitting calorimeter data of several compressors. To validate the transient prediction-capability of compressors by these models, start-up and cycling measurements were carried out and compared with the computed data. Due to the common requirements in cycle simulation tools, a model for the discharge temperature was developed and validated additionally. The goal of the present study is to find a combination of accurate models of mass flow rate, compressor power and discharge temperature which can be applied to cycle simulations of the whole refrigeration system.