Closed loop

Closed loop heat pump systems in DryFiciency 

Three novel heat pump demonstrators will be elaborated in the project. Each of the demonstrators will be designed, constructed and commissioned at the respective industrial site and operated under real industrial conditions. This page describes the two closed loop heat pump systems of DryFiciency. 


1. Closed loop heat pump with screw compressor

The first of the two DryFiciency closed loop systems is an advanced high-temperature industrial heat pump with a number of innovative components adapted exclusively for the DryFiciency project. These include a semi-hermetic screw compressor by Bitzer, which has been modified to high-temperature applications (for example by choosing compatible sealing materials). The refrigeration oil is provided and fine-tuned by FUCHS to guarantee the durability, miscibility, wear protection and viscosity required by the compressor. Chemours’ refrigerant Opteon MZ (HFO 1336mzz-Z), with a low global warming potential, was designed for applications with an evaporation temperature of around 50 to 120 °C, and a condensation temperature of around 100 to 160 °C. This closed-loop heat pump system will be demonstrated at Agrana Stärke GmbH in its starch drying process. 


2. Closed loop heat pump with piston compressor

The second of the DryFiciency heat pump systems includes the advanced high-temperature compressor (HBC 511) developed by Viking Heat Engines. The commercially available compressor is based on a proven, heavy-duty design developed in collaboration with the world's largest engine design company, AVL. The compressor has been engineered to operate at very high pressures and internal temperatures (above 160°C). It's compatible with all common refrigerants of the 3rd and 4th generations (e.g. HFO’s like 1336mzz-Z). The compressor has Internal oil circuit with oil filter and preheater and very low internal friction through exclusive use of low-friction bearings. It also has an efficient integrated water-cooled synchronous motor (PMM) and reaches a high isentropic and volumetric efficiency over a broad range of operating conditions by utilizing a variable speed operation. This closed-loop heat pump system will be demonstrated at Wienerberger GmbH in its brick drying process.

The heat pump demonstrator will have a heating capacity of around 400 kW, which is about 10% of the heat demand of the dryer. The heat supply temperatures will be in the range of 90-160°C. The heat pump demo plant will decrease end energy consumption by 2700 MWh/a and CO2 emissions by 530 t/a. 


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