Micro polygeneration utilizing renewable energy is a suitable approach to reduce energy consumption and carbon emission by offering high-efficiency performance, offsetting the need for centrally-generated grid electricity and avoiding transmission/distribution losses associated with it. This paper investigates the energy and environmental potential of a renewable trigeneration system in a residential application under Incheon (Korea) and Ottawa (Canada) weather conditions. The trigeneration system consists of a ground-to-air heat exchanger (GAHX), photovoltaic thermal (PVT) panels and an air-to-water heat pump (AWHP). The study is performed by simulations in TRNSYS (Version 17.02) environment. The performance of the trigeneration system is compared to a reference conventional system that utilizes a boiler for space and domestic hot water heating and a chiller for space cooling. Simulation results showed substantial annual primary energy savings from the renewable trigeneration system in comparison to the reference system-45% for Incheon and 42% for Ottawa. The CO 2eq emission reduction from the renewable trigeneration system is also significant, standing at 43% for Incheon and 82% for Ottawa. Furthermore, trigeneration systems' capability to generate electricity and thermal energy at the point of use is considered as an attractive option for inclusion in the future smart energy network applications.

Ground-air heat exchangers have become an important topic in recent years due to their contributions to the market growth of the ground source heat pump industry. This paper provides a comprehensive study and recommends suggestions on the selection process of a suitable pipe for an air-to-water heat pump (AWHP). Parametric studies including material, turbulent plate quantity, and pipe type were performed to identify an optimal pipe design for high-performance AWHP. Both numerical and experimental studies were carried out to validate current pipe models. Overall, there was good agreement between the numerical model and experimental results. It was determined that a spirally corrugated pipe exhibited excellent thermal power generation with little compromising pressure drop. Finally, a pipe selection example was demonstrated as a design guideline to size an optimal pipe for AWHP application.

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