Integrated Solar-Assisted Heat Pumps for water heating coupled to gas burners; control criteria for dynamic operation

摘要

A direct expansion integrated solar-assisted heat pump (ISAHP) is compared to a traditional flat platesolar panel for low temperature (45 C) water heating applications. The (simulated) comparison isaccomplished assuming both the devices are energy supplemented with an auxiliary standard gasburner, to provide the typical heat duty of a four-member family. Literature dynamical models of thesystems involved have been used to calculate the main performance figures in a context of actual climaticconditions and typical stochastic user demand.The paper highlights new heat pump control concepts, needed when maximum energy savings are themain goal of the apparatus for given user demand. Simulations confirm the high collector efficiency ofthe ISAHP when its panel/evaporator works at temperature close to the ambient one. The device, withrespect to a flat plate solar water heater, shows a doubled performance, so that it can do the same taskjust using an unglazed panel with roughly half of the surface.