Abstract

Organic Rankine cycle (ORC) is considered the most used technology in low temperature heat recovery units for cogeneration (electricity and cold). In this study, the effect of the operating parameters, in particular the condensation and the vaporization temperatures on the performance of the cycle are analyzed. In addition, we developed a new combination of organic Rankine cycle and vapor compresion cycle systems to make cogeneration with a negative cold (-10–0◦C), as well with a positive cold (0–10◦C). Three configurations are examined and studied in terms of energy efficiency, namely the performance of each configuration including net power, refrigeration capacity and overall efficiency, the thermal efficiency for ORC and the coefficient of performance for VCC. The used working fluids are n-hexane for the ORC and R600 for the VCC. We also try to apply this new system to have the cogeneration with congelation temperatures. The results show that, for cogeneration with negative cold, among the three configurations that we have developed, the cycle with recovery is preferable in which it has a better energy performance. For a hot spring of 1000 kW, this cycle can provide simultaneously, a maximum net work of 17 kW and a maximum net cooling capacity of 160 kW and an overall coefficient of the order of 0.3. For the production of positive cold, among the three configurations that we have developed, the basic cycle (without recovery) is the most suitable. With the same sourceof heat a maximum net work of 65 kW and a net cooling capacity in the order of 1000 kW with a global coefficient in the order of 1.05 is obtained. Our system is not only limited to be exploited for a temperature range between -10 ◦C and 10 ◦C, but can also be used with other fluids for lower temperatures (congelation temperatures).