Experimental and modeling investigation of an organic Rankine cycle system based on the scroll expander

A comprehensive model for organic Rankine cycle (ORC) was presented in this work. Several sub-models were included. Fewer empirical coefficients were needed in the improved expander model than the previous one as several parameters were obtained directly from the actual structure parameters of scrolls. The Dalton's law was used to simulate the pressure in the liquid tank, consisting of partial pressures of non-condensable gas and saturated vapor. A spray cooling tower model was built to take account of the influence of environment temperature and humidity on the ORC operation and performance. The simulations agree well with the tested data. Then, the model was used to analyze the mismatch among components of the cycle and evaluated the potential optimizations to the ORC prototype. For the present ORC system, the model predicts that the output power can be doubled after the optimization measures are taken. The environment temperature and humidity apparently influence the system performance. The effect of humidity becomes significant at high environment temperature. The expander power can be decreased by one third when the humidity is increased from 50% to 90% in summer season. The present work provides the guidance for design and operation of the ORC system.