Next Article in Journal
The Effects of Padé Numerical Integration in Simulation of Conservative Chaotic Systems
Previous Article in Journal
Decision Tree Ensemble Method for Analyzing Traffic Accidents of Novice Drivers in Urban Areas
Previous Article in Special Issue
Thermodynamic Analysis of a Hybrid Power System Combining Kalina Cycle with Liquid Air Energy Storage
Article Menu

Export Article

Open AccessArticle
Entropy 2019, 21(4), 361; https://doi.org/10.3390/e21040361

From Entropy Generation to Exergy Efficiency at Varying Reference Environment Temperature: Case Study of an Air Handling Unit

Department of Building Energetics, Vilnius Gediminas Technical University, Sauletekio ave. 11, LT-10223 Vilnius, Lithuania
*
Author to whom correspondence should be addressed.
Received: 4 February 2019 / Revised: 28 March 2019 / Accepted: 30 March 2019 / Published: 3 April 2019
(This article belongs to the Special Issue Thermodynamic Approaches in Modern Engineering Systems)
  |  
PDF [10899 KB, uploaded 17 April 2019]
  |  

Abstract

The continuous energy transformation processes in heating, ventilation, and air conditioning systems of buildings are responsible for 36% of global final energy consumption. Tighter thermal insulation requirements for buildings have significantly reduced heat transfer losses. Unfortunately, this has little effect on energy demand for ventilation. On the basis of the First and the Second Law of Thermodynamics, the concepts of entropy and exergy are applied to the analysis of ventilation air handling unit (AHU) with a heat pump, in this paper. This study aims to develop a consistent approach for this purpose, taking into account the variations of reference temperature and temperatures of working fluids. An analytical investigation on entropy generation and exergy analysis are used, when exergy is determined by calculating coenthalpies and evaluating exergy flows and their directions. The results show that each component of the AHU has its individual character of generated entropy, destroyed exergy, and exergy efficiency variation. However, the evaporator of the heat pump and fans have unabated quantities of exergy destruction. The exergy efficiency of AHU decreases from 45–55% to 12–15% when outdoor air temperature is within the range of −30 to +10 °C, respectively. This helps to determine the conditions and components of improving the exergy efficiency of the AHU at variable real-world local climate conditions. The presented methodological approach could be used in the dynamic modelling software and contribute to a wider application of the Second Law of Thermodynamics in practice. View Full-Text
Keywords: heating, ventilation, and air conditioning (HVAC); air handling unit; energy efficiency; exergy efficiency; produced entropy; variable reference temperature; coenthalpy heating, ventilation, and air conditioning (HVAC); air handling unit; energy efficiency; exergy efficiency; produced entropy; variable reference temperature; coenthalpy
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
SciFeed

Share & Cite This Article

MDPI and ACS Style

Streckienė, G.; Martinaitis, V.; Bielskus, J. From Entropy Generation to Exergy Efficiency at Varying Reference Environment Temperature: Case Study of an Air Handling Unit. Entropy 2019, 21, 361.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Entropy EISSN 1099-4300 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top