Integration of a conical frustum PCM system for enhanced thermal energy storage in a diesel engine cogeneration system

An effective heat storage system was achieved by fabricating a 400-L cylindrical thermal energy storage (TES) tank equipped with 9 conical frustum containers. These conical frustum containers with PCM (CFC-PCM) contain paraffin wax in the upper third of the tank and water as the heat transfer fluid (HTF) in the circulation process. The TES tank was integrated with a 40 kW diesel generator, and experiments were conducted by operating the engine at six different loads. During the charging process, heat was recovered from the engine exhaust gases and jacket cooling water. The performance parameters were evaluated and reported based on the transient behavior of a hybrid sensible/latent TES tank under the charging process. The results showed that at 72.55% of the engine peak load, the energy utilization factor (EUF) and the exergy efficiency of the system were 91.17% and 81.22%, respectively. Although adding PCM to water only resulted in a 3% enhancement in heat storage capacity, it improved the durability of heat charging by providing thermal stratification and increasing charging efficiency compared to the reference state in some of the studied cases.