Numerical Investigation of Copper Foam Adsorption Beds Packed with MOF-801 for Space Cooling and Desalination Applications

In this paper, an emerging Metal Organic Framework adsorbent MOF-801 packed into a recently developed copper foamed adsorbent-bed is numerically investigated under different operating conditions and physical parameters and benchmarked against the widely used silica gel adsorbent. A numerical model using lumped dynamic modelling approach was developed and validated against experimental data. An enhancement in the effective thermal conductivity for MOF-801 and silica gel foam packed bed and hence an improvement for the overall performance. The MOF-801-based system showed a higher performance for desalination application with a maximum production of specific daily water production of 13 m3/ton·day compared to 9 m3/ton·day for the silica gel-based system. MOF-801-based system evidenced its competition in the cooling application, achieving enhancement for the specific cooling power 140% higher than silica gel-based system

Multi-objective optimisation of MOF-801 adsorbent packed into copper foamed bed for cooling and water desalination systems

Recently, there have been several endeavours to enhance the performance of the adsorption systems for cooling cum desalination by developing new materials and adsorbent bed designs. Therefore, this article contributes to the field by computationally studying the utilisation of state-of-the-art MOF-801 adsorbent packed into the emerging copper-foamed adsorbent bed heat exchanger and benchmarking its performance against that utilising silica gel baseline adsorbent. A multi-objective global optimisation aimed simultaneously at the best coefficient of performance, specific cooling power, and clean water productivity was undertaken. The optimisation was built on the insights from a broad parametric study for the geometric and operating conditions. Given the novelty of the adsorbent MOF-801 and bed design combination, a one-dimensional model was developed to imitate the heat transfer in the adsorbent bed and coupled with a previously validated empirical lumped analytical model for the adsorption system using the MATLAB platform. Using copper foam significantly enhanced the effective thermal performance of the adsorbent bed, improving the overall system performance under different operating conditions. Furthermore, the clean water productivity of the MOF-801-based system outperformed that of the SG-based system by 38%, as the former yielded 29.7 m3/(ton.day), while the latter 21.5 m3/(ton.day). Besides, the MOF-801-based system showed specific cooling power of 830.8 W/kg compared to 611.5 W/kg for the silica gel-based system. However, the cooling capacity per unit volume determined the systems’ form factor, and the coefficient of performance was respectively higher by 9.6% and 20.2% for the silica gel-based system than those of the MOF-801-based system, stemming from the low packing density of MOF-801

Adsorption Refrigeration Technologies

This chapter introduces a comprehensive overview about the principles, challenges and applications of adsorption refrigeration systems (ARSs), as a promising sustainable solution for many of cooling and heating applications. In addition to the features and the basics of ARSs, the following topics have been covered such as characteristics of working pairs, trends in improving the heat and mass transfer of the adsorber; advanced adsorption cycles and performance and operational data of some adsorption refrigeration applications. In some details, the operating range and the performance of ARSs are greatly affected by the employed working adsorbent/refrigerant pairs. Therefore, the study, development and optimum selection of adsorbent/refrigerant pairs, particularly the composite adsorbents, can lead to improving the performance and reliability of ARSs. Regarding the enhancement of heat and mass transfer in the adsorbent bed, two methods are commonly used: one is the development of adsorbents through different coating technologies or new materials such as metal-organic frameworks, and the second is the optimization of the adsorber geometrical parameters and cycle modes. Finally, a brief on some adsorption chillers applications have started to find their share in markets and driven by solar or waste heats

Productivity and Thermal Performance Enhancements of Hollow Fiber Water Gap Membrane Distillation Modules Using Helical Fiber Configuration: 3D Computational Fluid Dynamics Modeling

Although hollow fiber water gap membrane distillation (HF-WGMD) units offer certain advantages over other MD desalination systems, they still require enhancements in terms of distillate flux and productivity. Therefore, this work proposes a novel configuration by incorporating the helical turns of HF membranes within the water gap channel of the HF-WGMD modules. A fully coupled 3D CFD model is developed and validated to simulate the multifaceted energy conservations and diffusion mechanisms that are inherent to the transport phenomena in the proposed HF-WGMD module. Single and double helical HF membrane designs with different numbers of turns are compared to the reference modules of single and double straight HF membrane designs under various operational conditions. At a feed temperature of 70 °C, a noteworthy 11.4% enhancement in the distillate flux is observed when employing 20 helical turns, compared to the single straight HF membrane module. Furthermore, the specific productivity revealed a maximum enhancement of 46.2% when using 50 helical turns. The thermal performance of the proposed HF-WGMD module shows higher energy savings of up to 35% in specific thermal energy consumption for a one-stage module. Using three stages of single helical modules can increase the gain output ratio from 0.17 for the single stage to 0.37, which represents an increase of 117.6%. These findings indicate the high potential of the proposed approach in advancing the performance of HF-WGMD systems