Performance Evaluation of a Reciprocating Engine Based Chp System for Commercial Office Building

Combined Heat and Power (CHP) involves on-site or near-site generation of electricity by using gas-fired equipment along with utilization of waste thermal energy available from the power generation process and have the potential to achieve an overall system efficiency of 80% because of the utilization of thermal energy, that would otherwise be wasted, and the reduction of transmission, distribution and energy conversion losses. The latest advancement in small scale power generation components like reciprocating engines, microturbines and fuel cells combined with waste heat technologies such as absorption chillers, desiccant dehumidifiers and thermal storage has made CHP systems for commercial buildings more promising and attractive. The paper describes a reciprocating engine based CHP system designed and operated in a four-story commercial mediumsized office building that has been established as the CHP research and demonstration facility on the campus of the University of Maryland in College Park, MD, USA. The CHP system involves the integration of a new single 75 kW commercial engine generator with the existing liquid desiccant dehumidification system. The engine generator is connected parallel to the grid for supplying 75 kW of electrical power to the building while the combined waste heat recovered from the exhaust gases as well as the jacket water from the engine is used to heat a 50:50 ethyl glycol-water loop through a packaged heat recovery system used for the regeneration of the lithium chloride solution in the liquid desiccant system and the ethyl glycol-water solution is returned back to the engine. The liquid desiccant system dehumidifies outdoor air for mixing in the roof top unit mixed air chamber instead of untreated outdoor air. Technical challenges concerning electrical and control aspects that were related to modifications of the original CHP system and improvements to the original system design were described by the authors in a previous paper. This paper here discusses the preliminary experimental results and performance evaluation based on recent testing and data analysis of the new CHP system.