Performance and emission analysis of CI engine operated micro-trigeneration system for power, heating and space cooling

Abstract

To achieve an optimal solution for the current energy crisis, the world needs to focus more on (a) renewable sources of energy or (b) look for recycling/appropriate utilization of energy being wasted. An alarming amount of heat is wasted from exhaust systems of various engines – stationary or in automobiles. Trigeneration systems use waste heat from prime movers to generate heating and cooling along with power. They are more efficient, less polluting & more economical than conventional systems. This paper describes the performance and emission characteristics of a micro trigeneration system based on a single cylinder diesel engine. In this trigeneration system, in addition to the electricity generated from the genset, waste heat from hot exhaust gas of diesel engine was used to drive a combination of four units of Electrolux vapor absorption (VA) system for space cooling, and compact type heat exchanger was used for hot water production. The capacity and heat input of each unit of VA system was 51 L and 95 W respectively. A cabin (3' × 5' × 6') made of ply wood was fabricated as a space for cooling. The test results show that a temperature drop of 6.5 °C was obtained in cabin at full engine load about 6 h after system start up. The reduction of CO2 emission in kg per kWh of useful energy output was 53.83% in combined heating and power (CHP), 57.46% in combined cooling, heating and power (CCHP) and 8.02% in combined cooling and power (CCP) mode compared to that of single generation (power generation only) at full load. The decrease in specific fuel consumption was 53.24%, 51.29% and 6.89% in case of CHP, CCHP and CCP mode respectively compared to that in single generation at full load. From the exergetic point of view, exergy efficiency of either of the integrated systems was marginally higher compared to the traditional power generation system (single generation). Hence, the results show that micro trigeneration systems using single cylinder CI engine for power, heating and space cooling are very effective and that they can be projected as strategic means to achieve energy security and efficiency, with positive impact on economy, simultaneously reducing environmental threats, leading to sustainable development.