Effects of process air conditions and switching cycle period on dehumidification performance of desiccant-coated heat exchangers

Chang, Chih-Chang; Luo, Win‐Jet; Lu, Chi-Wen; Cheng, Yusheng; Tsai, Bo-Yi; Zhang, Lin

doi:10.1080/23744731.2016.1210971

Cited by 26 publications

(16 citation statements)

References 25 publications

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“…where T w,i and T w,o are the cooling water temperatures inlet and outlet, respectively, Cp w is the specific heat of water, and m w is the mass flow rate of water [32]. The overall HTC can be expressed as:…”

Section: Discussionmentioning

confidence: 99%

Condensation Heat Transfer of R-407C in Helical Coiled Tube Heat Exchanger

et al. 2020

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The results of an experimental study to evaluate the characteristics of R-407C thermofluid during condensation in a helically coiled copper tube heat exchanger are presented. The effects of saturation temperature (Tsat), and mass and heat fluxes of refrigerant R-407C on thermal performance and pressure drop were determined. The relationship between the refrigerant wall subcooling and heat transfer coefficients was also investigated. This paper reports the effect of the temperature of the water used as cooling medium on the heat transfer rate of condensing R-407C. The study was conducted with mass flux of R-407C in the range of 100–450 kg/m2s, mass flux of the coolant water in the range of 500–5000 kg/m2s and Tsat of 31 °C, 35 °C, and 39 °C. Compared with a straight smooth tube, the use of the helical coiled (helicoidal) tube increased the condensation rate with a corresponding pressure drop that depended on the value of Tsat of the refrigerant and temperature of the coolant.

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Section: Discussionmentioning

confidence: 99%

Condensation Heat Transfer of R-407C in Helical Coiled Tube Heat Exchanger

et al. 2020

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“…where E sol (MJ) is the total useful solar thermal energy available in a month, which can be obtained from the solar collector capacity Q sol (kW). Q sol (kW) can be calculated by Equation (10).…”

Section: Of 18mentioning

confidence: 99%

Performance Enhancement of Hybrid Solid Desiccant Cooling Systems by Integrating Solar Water Collectors in Taiwan

et al. 2019

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A hybrid solid desiccant cooling system (SDCS), which combines a solid desiccant system and a vapor compression system, is considered to be an excellent alternative for commercial and residential air conditioning systems. In this study, a solar-assisted hybrid SDCS system was developed in which solar-heated water is used as an additional heat source for the regeneration process, in addition to recovering heat from the condenser of an integrated heat pump. A solar thermal collector sub-system is used to generate solar regeneration water. Experiments were conducted in the typically hot and humid weather of Taichung, Taiwan, from the spring to fall seasons. The experimental results show that the overall performance of the system in terms of power consumption can be enhanced by approximately 10% by integrating a solar-heated water heat exchanger in comparison to the hybrid SDCS system. The results show that the system performs better when the outdoor humidity ratio is large. In addition, regarding the effect of ambient temperature on the coefficient of performance (COP) of the systems, a critical value of outdoor temperature exists. The COP of the systems gradually rises with the increase in ambient temperature. However, when the ambient temperature is greater than the critical value, the COP gradually decreases with the increase in ambient temperature. The critical outdoor temperature of the hybrid SDCS is from 26 °C to 27 °C, and the critical temperature of the solar-assisted hybrid SDCS is from 27 °C to 30 °C.

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“…However, these studies have mainly focused on energy savings in terms of the hot water supply. In addition to hot water generation, a heat pump system can be designed to perform various operational functions including space cooling, space heating, hot water generation and other composite functions [11,12]. Hitunnen et al [13] utilized EnergyPRO software to simulate the recovered waste energy of heat source from heat pump.…”

Section: Introductionmentioning

confidence: 99%

Water Heating and Operational Mode Switching Effects on the Performance of a Multifunctional Heat Pump

Luo

Huang

et al. 2020

Energies

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In this study, a multifunctional air and water source heat pump system was developed with a parallel refrigerant piping arrangement, which possessed six operational functions: space cooling (SC), space heating (SH), water heating (WH), water cooling (WC) and two composite operational modes. The two composite operational modes were the SC/WH mode and the SH/WH mode. The performance of the multifuctional heat pump system under different ambient conditions was investigated based on the testing standards of CNS 14464 and CNS 15466. In this study, the effect of the direct water heating (DWH) and circulating water heating (CWH) methods on the performance was investigated. It was found that the water heating performance of the system by the DWH method is better than that of the system by the CWH method. The water heating capacity and COPw,h of the DWH method can be improvement by 2.6% to 22.1% and 2.9% to 50.8%, respectively. Moreover, this study developed a refrigerant pressure balance method to achieve an effective steady state of the refrigerant pressure after operational mode switching. By the refrigerant pressure balance method, the required time to attain the steady state could be greatly reduced—by 50%. However, the deviation of the refrigerant mass flow rate between the refrigerant pressure balance method and the refrigerant pump down method after operational mode switching ranged from 0.15% to 7.6%.

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Effects of process air conditions and switching cycle period on dehumidification performance of desiccant-coated heat exchangers

Cited by 26 publications

References 25 publications

Condensation Heat Transfer of R-407C in Helical Coiled Tube Heat Exchanger

Condensation Heat Transfer of R-407C in Helical Coiled Tube Heat Exchanger

Performance Enhancement of Hybrid Solid Desiccant Cooling Systems by Integrating Solar Water Collectors in Taiwan

Water Heating and Operational Mode Switching Effects on the Performance of a Multifunctional Heat Pump

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