City Research Online

Abstract

In this research, a new power system is proposed which is formed of an organic Rankine cycle combined with a shallow ground-cooled condenser. The aim is to investigate a ground-based cooling system to enhance the performance of the power cycle in terms of net output power. This combination is beneficial for power generation, especially in summer because the ground is more effective than that of the ambient air as a heat sink for the condenser due to its lower temperature. A primary heat rejector is also added to the cycle to ensure stability, avoid heat accumulation, and provide coolth compensation. The study includes experimental, analytical, and numerical investigations under several cycle conditions (temperatures and pressures) and working fluids (CO2, R123, R124, and R245fa). The experimental study was employed to examine the potential of shallow geothermal energy in Bekaa-Lebanon. The data collected from the experimental study was used as an input to the analytical and numerical analyses to assess the daily and annual performance. The software used are Engineering Equation Solver, Visual Basic and ANSYS Mechanical APDL. A cost analysis was carried out to evaluate the capital cost and payback period of the proposed system. The highest cycle’s performance was achieved while using R123 in which the net output power was enhanced by 31.5% considering a waste heat source (diesel generator) with exhaust gas temperature of 500°C and mass flow rate of 150 kg/hr. Based on the numerical simulations, the soil thermal interference radius was evaluated as ~0.32 m after 8 hours of operation which is considered as the maximum operating duration of the diesel generator. The corresponding average capital cost and payback period of the proposed system were estimated as £34,941 and 3.7 years, respectively.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) T Technology > TJ Mechanical engineering and machinery
Departments:	School of Science & Technology > Engineering > Mechanical Engineering & Aeronautics School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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