# Evaluation of Metal-Organic Frameworks as Potential Adsorbents for Solar Cooling Applications
## 8 Concluding Remarks  
Global energy consumption shows a continuous rise with households and buildings as major contributors to this increase. Due to improved living style and climatic changes, the demand for HVAC technology to provide indoor comfort conditions is increasing at a rapid rate. The reduction of energy consumption and the use of environment-friendly HVAC technology is a must to achieve low energy and sustainable goals. In this regard, adsorbent-based thermal cooling technology is a suitable alternative to conventional cooling systems. Adsorption-based cooling systems are available commercially and most of them use silica gel or zeolite as adsorbents because of their suitable adsorption characteristics. These systems currently face issues of lower performance and bulky nature. The development and promotion of these systems are directly related to their performance improvement. One way of achieving performance improvement is the development and utilization of new adsorbents such as MOFs. The MOF structures have recently received considerable interest due to their enhanced properties and structures. New concepts and reports have been published recently and successfully with the tools and promising applications for MOF. While the instability of MOFs could be a hurdle for their use as an adsorbent for cooling applications, to date many stable MOFs have been developed.  
This paper describes the exploration and production of MOF-based cooling technologies. The central idea of this study is to highlight the potential use of MOFs for adsorption and desiccant cooling systems. The potential of MOFs as adsorbents in adsorption-driven cooling is thoroughly accessed. The main findings of this paper can be summarized as:  
* Regardless of the type of adsorbent, a material with high uptake at lower partial pressure and having stepwise isotherm will be preferred for adsorption-based cooling applications. This type of adsorbent material will give better efficiency and performance.  
Figure 15: Adsorption and regeneration characteristics of MOFs.  
* The adsorption-based cooling with conventional adsorbent material such as silica gel or zeolites normally have a COP value less than one but the simulation studies available in the literature showed that the use of MOF in these technologies can help to achieve a coefficient of performance greater than one.
* Better adsorption characteristics, lower required heat, and stable nature has increased the interest of these materials to be used as adsorbents for cooling applications. MIL-101 Cr has a high water uptake capacity at low operating pressure and there will be only a slight decrease in its adsorption capacity over time.
* The results presented in the literature showed that HKUST-1 has 93.2% better uptake as compared to silica gel RD-2060. The high-water uptake capacity of HKUST-1 shows that it could be a suitable adsorbent material for adsorption-based cooling.
* Furthermore, the literature survey showed that Cu-BTC and CPO-27 are some of the other widely researched MOFs for their potential use as adsorbent materials for these applications.
* HKUST-1/water, MIL101/water, UiO-66/water, COF-5/ethanol and Maxsorb III/ethanol working pairs have the potential to increase the performance of adsorption cooling technologies.  
While MOF materials have a huge potential for adsorption-based cooling technologies, additional research is required to develop the perfect models to accurately predict the performance of MOF-based cooling systems.  
This research received no external funding.  
The authors declare no conflict of interest.