Power Plant Waste Heat Recovery for Household Heating Using Heat Pumps

Dosa, Ion (2014): Power Plant Waste Heat Recovery for Household Heating Using Heat Pumps. Published in: Publication of the MultiScience - XXVIII. microCAD International Multidisciplinary Scientific Conference (April 2014): pp. 1-8.

Abstract

This paper presents a model of a power plant condenser cooling circuit which has in addition to the classical cooling scheme heat pumps for waste heat recovery. Major source of loss for a thermal power plant is the heat rejected by the condenser which can be up to 48.9% of thermal energy at turbine inlet, depending on technology used for power generation. Heat rejected by the cooling water of condenser will end up in the environment through the use of a cooling tower or directly in rivers depending on the cooling scheme employed, producing thermal pollution. Based on the mathematical model, a study on the effect of heat recovery using power plant waste heat as heat source for heat pumps was carried out. The reference heat source temperature for the heat pump was 5 °C, while the condenser cooling water temperature at outlet was in the range of 22.96 °C in April to 14.99 °C in December. As expected high cooling water temperatures at condenser outlet will generate the highest practical COP which is 3.35 comparative to 2.84 for the reference case. Accordingly the smallest amount of work that needs to be supplied to the heat pump is 8.359 kW comparative to 9.861 kW for the reference case, resulting 1.502 kW savings. For the heating period from October to April the worst case scenario is for the temperatures in December when temperature of water at the outlet of condenser was minimal 14.99 °C. Even in this case, practical COP is 3.11 higher than 2.84 for reference case, and the amount of savings with the work supplied to heat pump is 0.869 kW. In closed loop operation, the temperature of returned water at the steam condenser inlet can be theoretically 5 °C (temperature at the outlet of heat pump evaporator) with all the benefits resulting from proper condenser cooling.

• Item Type: MPRA Paper
• Language: English
• Keywords: waste heat, heat recovery, heat pump, condenser cooling
• Subjects: C - Mathematical and Quantitative Methods > C6 - Mathematical Methods ; Programming Models ; Mathematical and Simulation Modeling > C63 - Computational Techniques ; Simulation Modeling

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