Free piston Stirling coolers have the advantages of high energy efficiency, environmental friendliness, wide cooling temperature range and easily-controlled cooling capacity, which is very attractive ...for deep-freezing applications. From the perspective of enhancing its competitiveness, here reports the use of wound wire mesh instead of the conventional stacked wire mesh to fill the regenerator, which brings low material waste, simplified manufacturing process and low flow resistance. In order to optimize the performance, a method of squeezing the bulges with variable heights into the mesh to adjust the porosity is used. A numerical model of cooler is first established to assist the system design, then experiments are done and compared with the simulation results. In the experiments, a coefficient of performance using wound wire mesh regenerator with a porosity of 72.7% is 0.8 at 102 W@-38 °C and 0.25 at 45 W@-80 °C, respectively. Though the comparison with stacked wire mesh regenerator shows that it leads to a relatively worse performance, the cooling performance is still comparable to that of vapor-compression refrigerators in the deep-freezing temperature region. Through further optimization, the application of wound wire mesh is promising.
•A free piston Stirling cooler with wound wire mesh regenerator is developed.•The wound structure brings low material waste, simplified manufacturing process and low flow resistance.•A novel method to adjust the porosity for optimization is used.•Coefficient of performance is 0.8 at 102 W@-38 °C and 0.25 at 45 W@-80 °C.
Low energy and sustainable alternative air conditioning systems are getting more and more attention due to climate change concerns. High effectiveness, low cost and compact heat and mass exchangers ...play an important role in making such technology competitive with conventional technologies. This communication describes a novel counter-flow liquid-gas contacting device, which uses highly porous and rotating cylindrical contact media made from wire screens. The device can have very high surface area density, exceeding 500 m2/m3. The device can be used as a modular evaporative cooler, indirect evaporative cooler as well as liquid desiccant based air dehumidification system. Low pressure drops across device, low electrical power consumption, ability to run on solar PV cells, least chances of liquid carryover and prospective high effectiveness are the important features of this device. The small modular device with 110mm diameter and half a meter length could provide cooling at a rate exceeding 200W in evaporative cooling experiment with consumption of 10W power. The effectiveness exceeding 50% could be achieved under moderately hot and dry conditions. Better performance is expected for dry and hot summer conditions. Preliminary trials for combined direct and indirect evaporative cooling and liquid desiccant dehumidifier are also taken and encouraging results are achieved.
This paper presents a comprehensive taxonomy and assessment of existing and emerging space cooling technologies in Europe. The study aims to categorize 32 alternative space cooling technologies based ...on eight scouting parameters (physical energy form, basic working/operating principle, refrigerant or heat transfer medium, phase of the working fluid, specific physical process/device, type of space cooling technology, fuel type and technology readiness level) and evaluate their key characteristics and development trends. The increasing demand for space cooling in Europe necessitates a thorough understanding of these technologies and their potential for energy efficiency. The majority of space cooling demand in Europe is currently met by conventional vapour compression systems, while a small portion is covered by thermally-driven heat pumps. The study reveals that several alternative space cooling technologies show promise for energy-efficient cooling but are not yet competitive with vapour compression systems in terms of efficiency and cost in the short-term and medium-term. However, technologies such as membrane heat pumps, thermionic systems, thermotunnel systems, and evaporative liquid desiccant systems demonstrate cost-competitiveness and energy efficiency in specific applications. The findings highlight the need for further research and development to improve the efficiency, costs, and market competitiveness of alternative space cooling technologies. The study also emphasizes the importance of policy support and the urgency to reduce greenhouse gas emissions, which can drive the adoption and advancement of sustainable cooling solutions.
•The study provides a taxonomy of 32 space cooling technologies in the EU•Eight scouting parameters are discussed to categorize the space cooling technologies•Most of the alternative technologies have potential but can't compete in efficiency and cost•Only ten of the alternative cooling technologies have a TRL between 5 and 9•Membrane heat pumps, thermionic systems, thermotunnel systems, and evaporative liquid desiccant systems are cost-competitive and energy-efficient in certain applications.
The aim of this study is to investigate, review, and assess the recent advances of alternative cooling technologies using traditional vapor compression (VC) systems as a baseline. Around 99% of the ...final energy consumption used for cooling in the current European market (European Union plus the United Kingdom (EU27 + UK) is supplied by VC technologies. In comparison, the remaining 1% is produced by thermally driven heat pumps (TDHPs). This study focuses on providing a complete taxonomy of cooling technologies. While the EU heating sector is broadly explored in scientific literature, a significant lack of data and information is present in the cooling sector. This study highlights technologies that can potentially compete and eventually replace VC systems within the decade (2030). Among others, the most promising of these are membrane heat pump, transcritical cycle, Reverse Brayton (Bell Coleman cycle), and absorption cooling. However, the latter mentioned technologies still need further research and development (R&D) to become fully competitive with VC technologies. Notably, there are no alternative cooling technologies characterized by higher efficiency and less cost than VC technologies in the EU market.
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