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Energy Engineering - Theoretical and Practical Investigations of the Heat Transfer in Vertical Heat Exchangers in the Ground


Veröffentlichungsart
Begutachtete Publikation

Fakultät/Einrichtung
Natur und Technik

Verfasser
Smolen, Slawomir, Prof. Dr.-Ing.

Autor_innen, Jahr, Titel
Janusz T. Cieslinski, Gdansk University of Technology, Gdansk, Polen,
Slawomir Smolen, University of Applied Sciences Bremen

Weitere Informationen
Developments in Mechanical Engineering, Volume 4
ISBN 978-83-7348-301-9

Anmerkung
Volume 4


Theoretical and Practical Investigations of Heat Transfer in Vertcal Heat Exchangers in the Ground

Introduction
In comparison to the other alternatives under consideration the ground represents one of the most efficient low temperature heat sources for heat pumps. In Europe and North America earth-coupled heat pumps have come to be widespread, and in many fields of application, especially in the power range of 6 to 12 (20) kW they have become an economical alternative to heat generators operated by gas or oil. By the use of efficient and well-designed heat pump systems savings of primary energy in the order of 30 to 45% as compared to oil-operated boilers, and 20 to 30% as to gas-operated condensing boilers can be achieved. Apart from this the emissions are shifted to central or decentralized power plants, which are continuously being modernized and equipped with more and more efficient waste gas purification systems, and those are thus reduced. At the same time the rising share of renewable energies in global electrical energy generation positively affects the environmental friendliness of electrically operated heat pumps.

In complex heating and cooling systems the ground can also be used as a "heat sink" and energy store. In geothermal systems close to the surface different heat exchange systems are being tested and employed. In the framework of the author's own research vertical heat exchangers with their own heat carrier medium/agent and direct evaporation have been investigated and analyzed.

The present analysis focuses mainly on the efficiency of the heat transfer in the soil as the most important component of the whole energy conversion process, consisting of the heat intake at the heat source, its transformation to a higher temperature level in the heat pump, and its use in heating systems (e.g. underfloor heating). The research activities connected to this require theoretical calculation models as well as practical trial runs to verify the theoretical results. One of the most important practical aspects is the investigation of the changing properties of the soil over a longer period of time; all these changes may have serious effects on the heat transfer process, and thus on the overall efficiency of the energy conversion chain.

 

 

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