In order to compare the performance of the carbon dioxide and HFC-125 heat pumps for medium-and high-temperature heating, both heat pump cycles were optimized using a simulation method. To fairly compare the performance of the cycles by using different working fluids, each cycle was optimized from the viewpoint of heating COP by two design parameters. The first is the gas cooler exit temperatur...

Abstract High‐temperature heat pumps (HTHPs) that can supply at temperatures and above 200°C have the potential to increase energy efficiency decrease carbon dioxide (CO 2 ) emissions in industrial processes. In this study, three reversed Rankine cycles using water vapor (R‐718) as working medium, with different intercooling strategies, were proposed their performance has been investigated. The...

Gas-driven sorption heat pumps (GDSHPs) exhibit possibilities in the reduction of energy use and environmental impact of heating systems that utilise natural gas. By utilising renewable thermal energy from the environment, that is, air, ground or water sources, significant reduction of primary energy use can be achieved. However, high cost, low coefficient of performance (COP) and large volume ...

Liquid recirculation is a method of improving evaporator performance by supplying the evaporator with more liquid than is evaporated. The excess liquid, which is generally provided by means of an externally-driven, mechanical pump, eliminates dryout and increases overall heat transfer coefficient in the evaporator. Liquid recirculation is common in large-scale industrial refrigeration systems, ...

Thermal plants operating on the Rankine cycle are by far the most common method of global electrical power generation. The Rankine cycle, first developed in the late 19 century, continues to this day to be one of the most important practical implementations of a heat engine. Innovation and enhancement of this cycle continue and today’s emphasis is directed towards reduced carbon emissions from ...

in the present study, saffron was dried using a heat pump-assisted hybrid photovoltaic-thermal solar dryer. the effect of different drying air temperatures at three levels (40, 50, and 60oc) and two different modes of the dryer (with and without heat pump system) were investigated on drying behaviour of saffron. after collecting the pertinent data, eleven drying models were used to describe dry...

A prototype compressor for application in high temperature compression-resorption heat pumps has been designed, manufactured and tested. The paper presents details of the compressor design together with test results obtained on the pilot heat pump plant with the prototype compressor. The compressor is of the twin-screw type and its stainless steel rotors operate without timing gears. There is n...