Cooling and power systems integrating organic Rankine cycle and chemisorption technologies

Abstract

Innovative cooling and power systems combining ORC and chemisorption cycles have been studied for the recovery of low-grade heat energy. A comprehensive literature review has been carried out summarising the previous reports with various low-grade heat driven systems, especially the chemisorption refrigeration and ORC technologies with their features, advantages and challenges. An ORC-Adsorption (ORC-AD) coupling system has been proposed and thermodynamically studied the performance indicators such as net power, refrigeration and thermal efficiency of the system. The results demonstrate that the combination of ORC and chemisorption technology can effectively improve the utilisation of the low-grade heat. In the study, novel chemisorption adsorbents have been developed by adding carbon-coated Nickel, Aluminium and Iron (Ni@C, Al@C and Fe@C) into the conventional SrCl2-EG and MnCl2-EG. Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray spectroscopy (EDX) have been used to observe the surface morphology of the adsorbents, while the thermal diffusivity and conductivity are tested by Laser Flash Analysis (LFA). It demonstrates a higher thermal conductivity of the novel sorbent. The sorption performance of the prepared sorbents has been tested. The results reveal the developed novel chemisorption composite that utilising Ni@C can effectively decrease cycle time and enhance the overall energy efficiency. Based on the experimental results, further system evaluation has been conducted by a simulation study. Cogeneration systems including ORC-AD, AD-ORC, ORC-resorption and resorption-ORC have been compared to evaluate different integrated cycles. Results show that AD-ORC and resorption-ORC have potential advantages over ORC-AD and ORC-resorption. Finally, the simulation model using MnCl2-EG-Ni@C as the sorbent has been applied in resorption-ORC, showing a large improvement of the system performance.