Metal organic framework material adsorption system for cooling, desalination and heat storage applications

Saleh, Majdi Massoud Idris (2021). Metal organic framework material adsorption system for cooling, desalination and heat storage applications. University of Birmingham. Ph.D.

Saleh2021PhD.pdf
Text - Accepted Version
Restricted to Repository staff only until 1 December 2026.
Available under License All rights reserved.
Download (10MB) | Request a copy

Abstract

Recently there have been significant interests in adsorption technologies for cooling, water desalination and heat storage. Adsorption systems have the advantages of (i) natural refrigerants such as water and ammonia that cause no ozone depletion or global warming effects, (ii) using low temperature heat sources like solar, geothermal and waste heat from industrial processes, (iii) having almost no moving parts and (iv) are free of vibration compared to conventional systems. However, the currently available adsorption systems suffer from low performance, being large and high capital cost, which hindered their widespread utilization.

Commercially available adsorption systems utilize adsorbent materials such as Silica gel and zeolite that suffer from the high desorption temperature for the later and the lower hydrophilicity of the former. To avoid these problems Aluminium fumarate Metal-Organic Frameworks (MOFs) material is used in this study as a promising new adsorbent material with water uptake higher than those of Silica gel and zeolites.

Furthermore, this research focuses on the development of new wire finned heat exchangers for adsorption beds using computational fluid dynamics simulation and experimental testing. COMSOL Multiphysics software was used to investigate the effect of wire fin height, wire fin spacing and tube diameter on the water vapour uptake during the adsorption process and the heat transfer to the adsorbent material to obtain the optimum design for the wire finned heat exchanger. Results revealed that the optimum design of wire finned heat exchanger is fin height 3.5 mm, fin spacing 1 mm and tube diameter of 6 mm. Also, CFD modelling was used to investigate the effect of coating the adsorbent material on the wire finned heat exchanger. This includes the effect of thickness of the adsorbent material, wire fin height, wire fin spacing, wire fin thickness, tube diameter and wire fin loops number on the water vapour uptake and the adsorbent material temperature. Results indicate that highest water uptake was achieved with adsorbent layer thickness of 0.3 mm, wire fin height of 7 mm, wire fin spacing of 1 mm, wire fin tube diameter of 1 mm and wire fin loops number of 21.

The optimum design of wire finned heat exchanger was manufactured and coated with Aluminium fumarate and then experimentally tested in a one bed adsorption system at different operating condition including half cycle time, evaporator water inlet temperature, condenser cooling water inlet temperature, adsorption cooling water inlet temperature and desorption hot water inlet temperature. The results indicate that the performance of the one bed adsorption system increases with increasing the chilled water inlet temperature and desorption bed heating water inlet temperature while it decreases with increasing the adsorption bed cooling water inlet temperature and condenser cooling water inlet temperature.

Also, work was carried out to compare the performance of the developed coated wire finned heat exchanger to coated rectangular finned and packed rectangular finned heat exchangers using Aluminium fumarate and the same one bed adsorption system. Results show that the coated wire finned heat exchanger outperformed the coated and packed rectangular finned heat exchangers in terms of Specific Cooling Power (SCP), Specific Daily Water Production (SDWP) of desalinated water, Coefficient of Performance (COP) and energy storage density (ESD). For water desalination, the coated wire finned heat exchanger produced highest SDWP of 23.5 compared to 17.2 and 12.7 m\(^3\)/ton/day for the coated and packed rectangular finned heat exchangers, respectively. For cooling applications, the coated wire finned heat exchanger produced highest SCP and COP of 682 W/kg, 0.32 compared to 671 W/kg, 0.11 and 318.5 W/kg, 0.23 for the coated and packed rectangular finned heat exchangers, respectively. For energy storage, the coated wire finned heat exchanger produced highest ESD of 2361 W.h/kg compared to 2266 and 870 for the coated and packed rectangular finned heat exchangers, respectively at half cycle time 2700 s.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):