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In an adsorption chiller, the refrigerant (water) operating pressure is low (0.5–5 kPa) and the cooling power generation of a flooded evaporator is affected by the height of water column. To resolve this issue, we experimentally investigate the performance of a flooded evaporator as a function of water height. The results show an optimum water height equal to 80% of the tube diameter leading to achieve the highest cooling power. Under this condition, the internal and external thermal resistances on the inside and outside of the evaporator tubes account for up to 73% of the overall thermal resistance. To reduce the internal thermal resistance, twisted and Z-type turbulent flow generators are incorporated into the evaporator tubes. The evaporator cooling power shows an increase by 12% and 58% when twisted tape and Z-type turbulators are used at a cost of an increase in the internal pressure drop by 2.5 and 14.5 times, respectively. The twisted tape and Z-type turbulators improve the average specific cooling power of the adsorption chiller by 9% and 47%, respectively. To reduce the external thermal resistance, the outside surface of the evaporator tubes is coated with porous copper. The coated evaporator increases the overall heat transfer coefficient by 1.4 times and improves the specific cooling power of the adsorption chiller by 48% compared to the uncoated tubes. [ABSTRACT FROM AUTHOR]

Thermoelectric self-cooling was firstly conceived to increase, without electricity consumption, the cooling power of passive cooling systems. This paper studies the combination of heat pipe exchangers and thermoelectric self-cooling, and demonstrates its applicability to the cooling of power electronics. Experimental tests indicate that source-to-ambient thermal resistance reduces by around 30% when thermoelectric self-cooling system is installed, compared to that of the heat pipe exchanger under natural convection. Neither additional electric power nor cooling fluids are required. This thermal resistance reaches 0.346 K/W for a heat flux of 24.1 kW/m 2 , being one order of magnitude lower than that obtained in previous designs. In addition, the system adapts to the cooling demand, reducing this thermal resistance for increasing heat. Simulation tests have indicated that simple system modifications allow relevant improvements in the cooling power. Replacement of a thermoelectric module with a thermal bridge leads to 33.54 kW/m 2 of top cooling power. Likewise, thermoelectric modules with shorter legs and higher number of pairs lead to a top cooling power of 44.17 kW/m 2 . These results demonstrate the applicability of thermoelectric self-cooling to power electronics. [ABSTRACT FROM AUTHOR]

Most electronic cooling devices consist of two reservoirs linked by an energy filter, which only allows high-energy electrons to transport from the cold reservoir to the hot reservoir. Here we propose a new type of cooling device, in which a cold reservoir is connected with two hot reservoirs by two energy filters and cooling is achieved by simultaneously removing high energy electrons from and injecting low energy electrons into the cold reservoir. The effects of key parameters such as the chemical potential difference of two hot reservoirs, the center interval and half width of two energy filters, etc. on the performances of the cooling device are discussed in detail. The optimal operating regions of the device are determined. Compared with the traditional electronic cooling device with a single energy filter between the cold and hot reservoirs, the optimal cooling power is doubly enhanced without reducing the COP (coefficient of performance) of the system. [ABSTRACT FROM AUTHOR]

Based on CAES (compressed air energy storage) and PM (pneumatic motor), a novel tri-generation system (heat energy, mechanical energy and cooling power) is proposed in this paper. Both the cheap electricity generated at night and the excess power from undelivered renewable energy due to instability, can be stored as compressed air and hot water by the proposed system. When energy is in great demand, the compressed air stored in this system is released to drive PM to generate mechanical power. The discharged air from PM can be further utilized as valuable cooling power. Compared to conventional CAES systems, the biggest characteristic of the proposed system is that the discharged air usually abandoned is used as cooling power. In order to study the performances of this system, a thermodynamic analysis and an experimental investigation are carried out. The thermodynamic model is validated by the experimental data. Using the validated thermodynamic model, the mechanical energy output, cooling capacity and temperature of discharged air, as well as the efficiency of the system are analyzed. The theoretical analysis indicates that the additional application of discharged air can improve total energy efficiency by 20–30%. Therefore, this system is very worthy of consideration and being popularized. [ABSTRACT FROM AUTHOR]