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Analytical expressions for optimum flow rates in evaporators and condensers of heat pumping systems
KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
2010 (English)In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 33, no 7, 1211-1220 p.Article in journal (Refereed) Published
Abstract [en]

The flow velocities on the air or liquid side of evaporators and condensers in refrigerating or heat pump systems affect the system performance considerably. Furthermore the velocity can often be chosen rather freely without obvious first cost implications. The purpose of the paper is to show analytical relations indicating possible optimum operating conditions. Considering a base case where the design data are known, simple analytical relations are deduced for optimum flow rates that will result in highest overall COP of the system when energy demand for the compressor as well as pumps or fans are included. This optimum is equivalent to the solution for minimum total energy demand of the system for a given cooling load. It is also shown that a different (and higher) flow rate will result in maximum net cooling capacity for a refrigerating system with fixed compressor speed. The expressions can be used for design purposes as well as for checking suitable flow velocities in existing plants. The relations may also be incorporated in algorithms for optimal operation of systems with variable speed compressors.

Place, publisher, year, edition, pages
2010. Vol. 33, no 7, 1211-1220 p.
Keyword [en]
Refrigeration system, Heat pump, Optimisation, Flow, Evaporator, Condenser, COP, Fan
National Category
Energy Engineering
URN: urn:nbn:se:kth:diva-26217DOI: 10.1016/j.ijrefrig.2010.05.009ISI: 000283567800002ScopusID: 2-s2.0-77957155032OAI: diva2:399482
QC 20110222Available from: 2011-02-22 Created: 2010-11-21 Last updated: 2011-02-22Bibliographically approved

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Granryd, Eric
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