Refrigeration Technology

Solar thermal chiller with parabolic trough collector system for vapour generation

The project developed an industrial refrigeration system consisting of a solar thermal parabolic trough collector system and a vapour-stream chiller. The collectors produce vapour at a temperature level of 200°C. Optimisation of the system's components contributes to improving the system's thermal ratio and reducing its heat loss.

 

Summary

The project's aim is the realisation of industrial refrigeration using a vapour-stream chiller. The required motive steam is generated using parabolic trough collectors connected to the vapour-stream chiller via heat exchangers. The first heat exchanger condenses the vapour from the parabolic troughs and the heat is transferred to a hot-water circuit for vapour generation. The condensate is cooled in the second heat exchanger, thus heating the water supplied to the vapour generator. Recooling is performed by a dry recooler with spray system.

The first project phase examined a number of media for suitability as motive vapour in the collectors and as refrigerant. Based on the analysis results, water was chosen as the motive and refrigerant medium. The parabolic troughs were operated using a 14% ammonia-water mixture. The collector's design was revised and tested in a collector field with 10 parabolic troughs. A fully automated vapour-stream chiller with a cooling power of 5 kWth was planned, designed and manufactured.

A general ecological benefit of the vapour-stream chiller lies in its use of solar power or waste heat as conventional chiller systems are presently powered almost exclusively using electricity.

Results:

  • The ammonia-water mixture is cheap, guarantees anti-freeze protection and displays a high vaporisation enthalpy as well as a high thermal capacity.
  • Operating the collectors in the wet-steam range is more expedient than using superheated water vapour.
  • The deeper-set aluminium segments of the collectors result in good contour accuracy of the mirrors.
  • The noble gas used in the receivers in which the solar radiation is converted to heat significantly reduces heat loss. 
  • The collector field can be operated reliably at 200°C collector supply temperature; a temperature of 200°C is reached at the collector output two minutes after switching the system on. 
  • Both parts of the plant – parabolic troughs and vapour-stream chiller – proved operable. Some of the parabolic trough components require optimisation in regard to long-term stability.

More Project Informations

Project titel : Solarthermische Kälteerzeugung mit Parabolrinnenkollektorsystem und Dampfstrahlkältemaschine

Project number: 01RI06001

Project period: 2006 - 2009

Project region: Germany (Bavaria)

Project contact:

Herr Dr.-Ing. Pollerberg

Frau Dipl.-Ing. Jähnig

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Source: German National Library of Science and Technology Hannover (TIB)