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WP4 - Heat pumps (Deliverable 4.3)

The full report is confidential and will not be distributed to the public. However, a brief summary of the contents are given here.

Within phase 3 of the MacSheep project three heat pump prototypes are under development by three different groups. These prototypes include several breakthroughs concerning advanced heat pump cycles, which have been identified and analyzed within phase 1 and phase 2 of the project, and which are documented in the Deliverables 4.1 and 4.2.

IWT, SPF and ESSA are developing a heat pump with a speed controlled compressor, a desuperheater and vapor injection (economizer cycle). A test rig of a first prototype has been built at IWT, which involves the above described breakthroughs and is equipped with extensive measurement devices in order to allow an in-depth analysis of the refrigerant cycle. First functional tests and measurements concerning the compressor performance have been performed and the results compared to manufacturer data.

The heat pump prototype will be extensively tested in 2014, starting with measurements of the compressor performance followed by an optimization of the whole refrigerant cylce. In parallel a heat pump model will be parametrised, validated and eventually adapted and/or extended.

Ratiotherm and SERC have developed and built a prototype of a two stage heat pump with intermediate storage, which is intended for the use in retrofit buildings. The two stages can operate in cascade mode (both running simultaneously) when required, or can run independently with heat from the lower (colder) stage being stored in the intermediate store. This store is also used for low grade heat from solar collectors. The developed prototype is currently undergoing testing at the Ratiotherm factory.

Once the measurements on the prototype have been completed, a simulation model of the heat pump system will be finalized and used for optimization. Costs for the different components in the heat pump will be used to determine the exact design (with or without storage) and thereafter the sizing of the finalized prototype. The use of variable speed compressors will be analyzed once the calibrated model of the prototype is available.

CTU and Regulus are developing a ground source heat pump with three heat exchangers on the sink side (desuperheater, condenser and subcooler). Each sink is used at a different temperature level: the desuperheater for DHW preparation, the condenser for space heating and the subcooler for cold water preheating. The target application of the concerned heat pump is the area of new or retrofitted family houses with a design heat load of up to 6 kW.

A crucial part for further development of the Regulus/CTU heat pump are the tests to be performed with the designed and assembled prototype.

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