Preliminary experimental investigation of a natural gas-fired ORC-based micro-CHP system for residential buildings

The continual increases in energy demand and greenhouse gas emissions, call for efficient use of energy resources. Decentralized combined heat and power (CHP) technology provides an alternative for the world to meet and solve energy-related problems including energy shortages, energy supply security, emission control and conservation of energy. This paper presents the preliminary results of an experimental investigation of a natural gas-fired micro-CHP system for residential buildings based on an organic Rankine cycle (ORC). Isopentane was used as the ORC working fluid in consideration of several criteria including its environmentally-friendly characteristics. Experiments were conducted to evaluate the performance of the developed system at different heat source temperatures of nominally 85, 80, 75, 70, and 65 °C. The maximum electrical power output of 77.4 W was generated at heating water entry temperature of 84.1 °C, corresponding to net cycle electrical efficiency of 1.66%. Further work will be done with a view to increasing the cycle electrical efficiency by using more efficient components, in particular the expander and generator. •A natural gas-fired ORC-based micro-scale CHP system has been developed and tested.•The good agreement between the mechanical and gross power validates the assumptions.•A vane expander suits a micro-CHP system based on an organic Rankine cycle.•A vane expander does not suit power generation by a Trilateral Flash Cycle (TFC).•Domestic gas-fired ORC systems may reduce reliance on central power stations.