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. 2021 Sep 30;23(10):1282.
doi: 10.3390/e23101282.

Energy and Entropy Analyses of a Pilot-Scale Dual Heating HDH Desalination System

Dahiru U Lawal  1 , Saad Abdul Jawad  2 , Mostafa H Sharqawy  3 , Mohamed A Antar  1   2
Affiliations

Energy and Entropy Analyses of a Pilot-Scale Dual Heating HDH Desalination System

Dahiru U Lawal et al. Entropy (Basel). .

Abstract

This study focuses on energy and entropy analysis to theoretically investigate the performance of a pilot scale dual heated humidification-dehumidification (HDH) desalination system. Two cases of HDH systems are considered in the analysis. The first case is a dual heated (DH) cycle consisting of 1.59 kW air heater and 1.42 kW water heater with a heat rate ratio of 0.89 (CAOW-DH-I). Whereas the second case is a dual heated HDH cycle comprising of 1.59 kW air heater and 2.82 kW water heater with a heat rate ratio of 1.77 (CAOW-DH-II). As a first step, mathematical code was developed based on heat and mass transfer and entropy generation within the major components of the system. The code was validated against the experimental data obtained from a pilot scale HDH system and was found to be in a good agreement with the experimental results. Theoretical results revealed that there is an optimal mass flowrate ratio at which GOR is maximized, and entropy generation is minimized. Furthermore, the degree of irreversibility within the humidifier component is low and approaches zero, while the specific entropy generation within other components are relatively high and are of the same order of magnitude. Entropy analysis also showed that the dual heated system with heat rate ratio greater than unity is better than the one with heat rate ratio less than unity.

Keywords: HDH; desalination; entropy generation; humidification-dehumidification; irreversibility analysis.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Schematic layout of Experimental Testing Rig.
Figure 2
Figure 2
Schematic Diagram of a Dual Heated HDH Cycle.
Figure 3
Figure 3
DH-I Cycle Theo & Exp: Mass flow rate ratio vs. gained output ratio.
Figure 4
Figure 4
DH-I Cycle Theo & Exp: Mass flow rate ratio vs. maximum cycle temperature.
Figure 5
Figure 5
DH-I Cycle Theo & Exp: Mass flow rate ratio vs. water temp. at hum. inlet.
Figure 6
Figure 6
DH-II Cycle Theo & Exp: Mass flow rate ratio vs. gained output ratio.
Figure 7
Figure 7
DH-II Cycle Theo & Exp: Mass flow rate ratio vs. maximum cycle temperature.
Figure 8
Figure 8
DH-II Cycle Theo & Exp: Mass flow rate ratio vs. water temp. at hum. inlet.
Figure 9
Figure 9
Specific entropy generation vs. MR for CAOW-DH-I and CAOW-DH-II.
Figure 10
Figure 10
GOR against the specific entropy generation for CAOW-DH-I and CAOW-DH-II.
Figure 11
Figure 11
Specific entropy generation in each component of CAOW-DH-I and CAOW-DH-II.
See this image and copyright information in PMC

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