Abstract
Development of a reliable and convenient dynamic modelling approach for ground source heat pumps remains as an important unresolved issue. As a remedy, in this work a novel, computationally-efficient modelling framework is developed and rigorously validated. This is based upon an implicit computational modelling approach of the ground together with an empirical modelling of heat and fluid flow inside U-tube ground heat exchangers and waste heat calculations. The coupled governing equations are solved simultaneously and the influences of parameters on the performance of the whole system are evaluated. The outcomes of the developed framework are, first, favorably compared against two different existing cases in the literature. Subsequently, the underground storage and recovery process of the waste heat through flue gases generated by a biomass combustion plant are modelled numerically. This reveals the history of temperature distributions in the ground under different configurations of the system. The results show that for a biomass combustion plant generating flue gases at 485.9 K as waste heat with the mass flow rate of 0.773 kg/s, the extracted heat from the ground is increase by 7.6%, 14.4% and 23.7% per unit length of the borehole corresponding to 40 °C, 50 °C and 60 °C storage temperatures. It is further shown that the proposed storage system can recover a significant fraction of the thermal energy otherwise wasted to the atmosphere. Hence, it practically offers a sizable reduction in greenhouse gas emissions.
Highlights
Renewable energy technologies are to respond to the substantial challenges of growing energy demands and emission of greenhouse gases [1]
The results show that for a biomass combustion plant generating flue gases at 485.9 K as waste heat with the mass flow rate of 0.773 kg/s, the extracted heat from the ground is increase by 7.6%, 14.4% and 23.7% per unit length of the borehole corresponding to 40 °C, 50 °C and 60 °C storage temperatures
The thermal efficiency is in the range of 60–90% for most industrial boilers, while a considerable fraction of thermal energy is often lost to atmosphere by the flue gases [4]
Summary
Renewable energy technologies are to respond to the substantial challenges of growing energy demands and emission of greenhouse gases [1]. COP GHE GSHP HTR PE coefficient of performance ground heat exchanger ground source heat pump heat transfer rate polyethylene usually increase by 10–30% due to the reduced heat transfer efficiency between the high-temperature flue gas and heat exchanges [6]. It follows that there is a significant potential to recover the waste heat of the flue gases from industrial boilers [6]. Novel, efficient and reliable framework should be developed to model thermal performance of GSHP systems To achieve these goals, ground storage of the thermal energy of exhaust, gasses generated by combustion of biomass, is modelled numerically. In comparison with other simulation techniques, the developed framework can solve complex problems of GSHP modelling faster and more accurately
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