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Gewählte Master / Diploma Thesis:

Christoph Göbl (2014): Aktive Wärmerückgewinnung bei Kälteanlagen durch den Einsatz von Hochtemperaturwärmepumpen.
Master / Diploma Thesis - Institut für Verfahrens- und Energietechnik (IVET), BOKU-Universität für Bodenkultur, pp 92. UB BOKU obvsg

Data Source: ZID Abstracts
Abstract:
In some companies there is a need of heat and cooling energy, at the same time. This is a suitable setting for the application of heat pumps. The first part of the present work deals with the state of the technology and the availability of high temperature heat pumps. It is shown, that heat pumps are available with target temperatures of nearly 100 °C. The second part deals with the integration of heat pumps in refrigration plants. There are two possibilities: Directly: A part flow of the refrigerant medium of the refrigeration plant is directly used after the compression. To get the requested temperature it will be compressed again. Indirectly: A part flow of the refrigerant medium of the refrigeration plant transfers its heat through a heat exchanger to the refrigerant medium of a conventional heat pump. For a specific application with a condensertemperature of the refrigeration plant of 28 °C and a heat utilisation temperature level of 95 °C, five models have been develeoped: Model 1: Direct use of the refrigerant medium of the refrigeration plant Model 2: Use of a heat pump with R717 as refrigerant medium Model 3: Use of a heat pump with R600a as refrigerant medium Model 4: Use of a heat pump with R245fa as refrigerant medium Model 5: Use of a two stage heat pump (refrigerant medium R134a/R245fa). From a thermodynamic point of view the direct use of the refrigerant (Model 1) is the most efficient one. A COP of 4,2 is possible. Also conventional heat pump systems with R717 and R245fa reach a COP of 3,8. Model 3 and 5 accomplish a COP of 3,5, which is also sufficient for such systems. The ecological evaluation shows that there are high CO2 savings, in comparison with gas or light fuel oil possible. Also from an economic point of view the change to a heat pump system leads to costs savings through the lower opperating costs. In conclusion, it is clear that a refrigeration plant is a very good heat source for high temperature heat pumps.

Beurteilende(r): Pröll Tobias

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