Authors: Vytautas Martinaitis; Giedre Streckiene
Addresses: Department of Building Energetics, Vilnius Gediminas Technical University, Sauletekio ave. 11, LT–10223 Vilnius, Lithuania ' Department of Building Energetics, Vilnius Gediminas Technical University, Sauletekio ave. 11, LT–10223 Vilnius, Lithuania
Abstract: The energy chain of building energy services begins with primary energy resources and ends with building services systems (BSS). The analysis for such chain and its' elements should rely on fundamentals of thermodynamics. This paper pays attention to one of them that exergy efficiency is in the range of 0-1. In this study, exergy analysis of heat recovery exchangers for air handling units is carried out. Special attention is paid to the direction of thermal exergy flow when temperatures inducing heat transfer are close to a near-environmental temperature. On the basis of the proposed methodology, the dependency of exergy efficiency on dimensionless temperature and thermal recuperator efficiency is discussed. It is important to take the dimensionless temperature interval 0-1 into account. Here the exergy efficiency values are the lowest. Design and management measures should be used to avoid operating a heat exchanger there.
Keywords: exergy analysis; exergy efficiency; heat recovery; heat exchangers; near-environmental temperature; Carnot factor; air handling units; heat transfer; dimensionless temperature interval; thermal recuperator efficiency.
International Journal of Exergy, 2016 Vol.20 No.3, pp.381 - 404
Received: 30 Apr 2015
Accepted: 19 Aug 2015
Published online: 29 Jun 2016 *