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21 results on '"Zhang, Yeqiang"'

8. Effect of Spray Amount on Spray Cooling Performance of Mobile AirConditioning Condenser

Author

Zhang Yeqiang, Li Kangli, Jiao Xiangzhi, Hu Gen, Liu Jinping, Qin Xiaoding, and Jin Tingxiang

Subjects
effect on performance, exergy, spray cooling, mobile air conditioner, Heating and ventilation. Air conditioning, TH7005-7699, Low temperature engineering. Cryogenic engineering. Refrigeration, TP480-498, Technology
Abstract

In a mobile air conditioner with a double air duct, two nozzles were installed at the lower left and lower right corners of the condenser respectively, for spray cooling. With an enthalpy difference experiment, the temperature at different state points, energy consumption and refrigerating capacity were tested with outdoor temperatures of 35 ℃/24 ℃ and indoor temperatures of 27 ℃/19 ℃ (dry bulb temperature/ wet bulb temperature), and the influence of different spray quantities from 0.55 g/s to 2.10 g/s on the performance of mobile air conditioning was analyzed. The results show that with the increase in spray quantity, the evaporating pressure was almost unchanged at 1.0 MPa, but the condensing pressure decreased from 3.45 MPa to 3.14 MPa, and the condensing temperature decreased from 55.5 ℃to 51.3 ℃. Moreover, energy consumption decreased from 1582.95 W to 1465.1 W, refrigerating capacity increased from 3090 W to 3339 W, and the EER increased from 1.95 to 2.28. The cold exergy was small and the exergy efficiency of the system was only 5.19% to 6.08% because of a small difference of only 8 ℃ between the indoor and ambient temperatures. Among the different components, the maximum exergy loss coefficient occurred in the compressor, which was 0.496, 0.472, 0.479 and 0.476, respectively, while the lowest exergy efficiency was obtained in the evaporator, which was only 24.6%–26.0% .

Published
2021
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12. Inner-pressure Ratio Adjustment of the Twin-screw Compressor in a High-temperature Heat Pump

Author

Xing Linfen, He Yongning, Cao Feng, Zhang Yeqiang, Yin Shujing, and Li Yaoquan

Subjects
high temperature heat pump, twin screw compressor, inner pressure ratio adjustment, vapor injection, Heating and ventilation. Air conditioning, TH7005-7699, Low temperature engineering. Cryogenic engineering. Refrigeration, TP480-498, Technology
Abstract

Changing the working conditions of an industrial heat pump can cause a mismatch of the inner and outer pressure ratios of the twin-screw compressor. Over-compression and under-compression increase the compressor power consumption and decrease the heat-pump’s coefficient of performance (COP). Injecting refrigerant vapor into the compression chamber would increase the inner-pressure ratio and avoid under-compression. An experimental study was conducted with different injection pressures when the condenser outlet’s water temperature reached 90 ℃. The results show that the optimal injection pressure causes the COP and adiabatic efficiency to peak at the same time. This result shows that the vapor injection changes the compression process to a quasi-polytropic compression process. Adjusting the compressor’s inner-pressure ratio by changing the refrigerant-injection pressure is feasible.

Published
2017
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16. Heat storage performance analysis of ZMS-Porous media/CaCl2/MgSO4 composite thermochemical heat storage materials

Author

Wang Feifei, Zhang Xueling, Zhang Qi, Jin Ting-xiang, Lei Xudong, Zhang Yeqiang, Cheng Chuanxiao, and Wang Yanling

Subjects
Materials science, Thermal conductivity, Adsorption, Differential scanning calorimetry, Chemical engineering, Renewable Energy, Sustainability and the Environment, Desorption, Mass transfer, Porous medium, Thermal energy storage, Mass fraction, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials
Abstract

A new composite thermochemical heat storage (TcHS) material was proposed herein with good heat storage performance and desirable stability, which was prepared by using solid-state cold pressing with a zeolite molecular sieve (ZMS) and two salts (CaCl2 and MgSO4). First, the optimized mass content (CaCl2:MgSO4 = 6:4) denoted Smix was obtained, which represents an equilibrium between the adsorption capacity and deliquescence. Then, two types of ZMS porous media: 13X and NaY were added to Smix to further prevent deliquescence and improve stability, respectively. An orthogonal experiment with four factors (mass fraction, pressure, temperature, and humidity) and three levels was used to test the optimal preparation conditions, and the optimal configurations were obtained for Xopt (13X-ZMS: CaCl2: MgSO4 = 10: 54: 36) and Yopt (NaY-ZMS: CaCl2: MgSO4 = 20: 48: 32). The optimized samples were measured by SEM, XRD and thermal conductivity tests, and the adsorption capacities for Smix, Xopt, and Yopt were found to follow the order of Xopt (0.449 g/g) > Smix (0.374 g/g) > Yopt (0.335 g/g). The accumulated void formation for the porous media can promote heat and mass transfer and can significantly improve the adsorption capacity and avoid deliquescence. Differential scanning calorimetry (DSC) results showed that the heat storage density (HSD) for Xopt (1414.49 J/g) is higher than that for Yopt (1097.02 J/g). Finally, 20 cycles showed that Xopt has good cycle stability based on the normalized ad/desorption mass (>1) and normalized desorption heat (>0.8). The results showed that Xopt shows application potential as a TcHS composite material in medium- and low-temperature thermochemical adsorption heat storage systems.

Published
2021
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17. Waste Heat Recovery from Diesel Engine Exhaust Using a Single-Screw Expander Organic Rankine Cycle System: Experimental Investigation of Exergy Destruction

Author

Zhang, Yeqiang, Lei, Biao, Masaud, Zubair, Imran, Muhammad, Wu, Yuting, Liu, Jinping, Qin, Xiaoding, Muhammad, Hafiz Ali, Zhang, Yeqiang, Lei, Biao, Masaud, Zubair, Imran, Muhammad, Wu, Yuting, Liu, Jinping, Qin, Xiaoding, and Muhammad, Hafiz Ali

Abstract

The organic Rankine cycle is a mature small-scale power generation technology for harnessing low- to mid-temperature heat sources. However, the low efficiency of the cycle still hinders its widespread implementation. To optimize the cycle’s performance, it is crucial to identify the source and magnitude of losses within each component of the cycle. This study, thus, aims to investigate the irreversible losses and their effect on the performance of the system. A prototype organic Rankine cycle (ORC) with the exhaust of a diesel engine as the heat source was developed to experimentally investigate the system and ascertain the losses. The experiments were performed at steady-state conditions at different evaporation pressures from 1300 kPa to 1600 kPa. The exergy loss and exergetic efficiency of the individual component and the overall system was estimated from the experimentally measurement of the pressure, temperature, and mass flow rate. The results indicate that the exergy losses of the evaporator are almost 60 kW at different evaporation pressures and the exergy loss rate is from 69.1% to 65.1%, which accounted for most of the total exergy loss rate in the organic Rankine cycle system. Meanwhile, the highest shaft efficiency and exergetic efficiency of the screw expander are 49.8% and 38.4%, respectively, and the exergy losses and exergy loss rate of the pump and pipe are less than 0.5 kW and 1%. Due to the relatively higher exergy loss of the evaporator and the low efficiency of expander, the highest exergetic efficiency of the organic Rankine cycle system is about 10.8%. The study concludes that the maximum improvement potential lies in the evaporator, followed by the expander.

Published
2020

19. Theoretical performance study on R600/R170 auto-cascade refrigeration cycle with mechanical pre-cooling

Author

He, Yongning, Cao, Wenliang, Wang, Su’ao, Xu, Ke, Kang, Xiangjie, Zhang, Yeqiang, Xing, Linfen, and Wu, Xuehong

Abstract

A mechanical pre-cooling auto-cascade refrigeration (PACR) system was proposed, R600a single-stage vapor compression system was used to provide pre-cooling for R600/R170 auto-cascade refrigeration (ACR) system. Performance of PACR system under different operating conditions was discussed. The result showed that maintaining a constant outlet temperature of 30°C for the condenser and −45°C for the evaporator in a PACR system resulted in an optimal intermediate temperature that maximized coefficient of cooling performance (COP). At this time, the optimal intermediate temperature of R600/R170 was 0°C, the COP maximum value (COPmax) was 0.693 and exergy efficiency (ηEx) was 20.9%. And as the evaporator outlet temperature decreases to −70°C, the optimal intermediate temperature decreases to −10°C. The cooling capacity (Qe) of the low-temperature grade circulating refrigerant in the PACR system using R600/R170 at different evaporation temperatures was increased by 86.3%–108% compared to that of R134a/R23. COPmaxwas increased by 7.1% compared to that of R134a/R23 at the evaporator outlet temperature of −60°C.

Published
2024
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