# A Review of Small-Scale Vapor Compression Refrigeration Technologies
## 5 Concluding Remarks  
The purpose of this review was to describe the current state of the art of miniature vapor compression refrigeration, showing experimental and modeling research work carried out in recent years both for complete systems as well as for individual components, considering the different applications proposed until now. An attempt was also made to give an overview of active and passive technologies available for small-scale cooling, evidencing the advantages of vapor compression over the others. The main conclusions obtained from this review are listed as follows:  
* Miniature vapor compression refrigeration appears to be the best option for many small-scale cooling applications due to advantages such as working over a wide range of operating temperatures, ability to cool down junction temperature below ambient, potential for high COP values, operation for long periods at large cooling capacity with low mass flow rates, and transport of heat away from its source. In addition, vapor compression is well suited for portable applications compared to alternative technologies that involve greater number of components and complexity.
* In the past decade, there has been a reduction in the number of research papers published on miniature vapor compression refrigeration research primarily directed toward cooling electronic components and personal cooling. However, alternative applications are currently being commercially offered in sectors such as medical, pharmaceutical, automotive, and food preservation, among others. Consequently, further research is necessary to validate their feasibility for both existing and prospective applications, facilitating widespread commercialization.
* It can be concluded that the challenges associated with component miniaturization have been a critical factor hindering widespread study and development of these systems. Many of the components used in the publications cited in this review were custom-built by researchers due to limited commercial availability, thus slowing technical progress. It is, however, anticipated that research will experience a resurgence in the coming years, given the current availability of both individual components and pre-assembled prototypes of miniature VCR systems in the market.
* The industrial sector has a strong need for effective thermal management and heat dissipation, while commercial, technical, technological, and normative aspects limit the applicability of small-scale refrigeration.
* It is finally observed that miniature vapor compression refrigeration has not reached maturity since there are still many areas to be explored, including, among others, evaluation of low GWP refrigerants, search for energy savings, improvements in energy efficiency, additive manufacturing, artificial intelligence, and integration with renewable energies. Some of these topics have been addressed for conventional refrigerators and now demand further development for application to miniature systems.  
Conceptualization, J.M.B.-F. and J.C.S.-R.; investigation, J.M.B.-F. and J.C.S.-R.; writing--original draft preparation, J.C.S.-R.; writing--review and editing, J.M.B.-F. and S.M.A. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
We acknowledge the University of Guanajuato (CIIC 2024) for their support in the realization of this work.  
The authors declare no conflict of interest.