Second law analysis of a diesel engine waste heat recovery with a combined sensible and latent heat storage system

• Published in: Energy policy Vol. 39; no. 10; pp. 6011 - 6020
• Main Authors: Pandiyarajan, V., Chinnappandian, M., Raghavan, V., Velraj, R.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-10-2011; Elsevier; Elsevier Science Ltd
• Series: Energy Policy
• Subjects: Applied sciences; Automobile industry; combustion; Diesel engines; Direct power generation; Discharge; Energy; Energy efficiency; Energy policy; Energy use; Energy. Thermal use of fuels; Engineering; Engines and turbines; Environment; Environmental economics; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Exergy; heat; Heat recovery systems; issues and policy; Latent heat; Phase change material; Storage systems; Studies; Thermal energy; Thermal energy storage; Transport and storage of energy; Waste heat recovery; Waste heat recovery Thermal energy storage Phase change material; Waste management; wastes; Waste heat recovery; Thermal energy storage; Phase change material; Latent heat storage; Diesel engine; Thermal energy; Heat recovery; Storage; Sensible heat storage; Exergy analysis; Thermodynamic analysis; PCM material; Waste heat
• ISSN: 0301-4215; 1873-6777
• DOI: 10.1016/j.enpol.2011.06.065

The exhaust gas from an internal combustion engine carries away about 30% of the heat of combustion. The energy available in the exit stream of many energy conversion devices goes as waste. The major technical constraint that prevents successful implementation of waste heat recovery is due to intermittent and time mismatched demand for and availability of energy. The present work deals with the use of exergy as an efficient tool to measure the quantity and quality of energy extracted from a diesel engine and stored in a combined sensible and latent heat storage system. This analysis is utilized to identify the sources of losses in useful energy within the components of the system considered, and provides a more realistic and meaningful assessment than the conventional energy analysis. The energy and exergy balance for the overall system is quantified and illustrated using energy and exergy flow diagrams. In order to study the discharge process in a thermal storage system, an illustrative example with two different cases is considered and analyzed, to quantify the destruction of exergy associated with the discharging process. The need for promoting exergy analysis through policy decision in the context of energy and environment crisis is also emphasized.
► WHR with TES system eliminates the mismatch between the supply of energy and demand. ► A saving of 15.2% of energy and 1.6% of exergy is achieved with PCM storage. ► Use of multiple PCMs with cascaded system increases energy and exergy efficiency.