Assessing the performance of a gas-water heat exchanger based on micro-heat pipe technology

ABSTRACT

The paper presents a gas-water heat exchanger based on the technology of a microheat pipe. The heat exchanger parameters, such as inlet and outlet temperature of flue gas, wind speed and inlet and outlet temperature of the water, were measured in practice. The analysis data showed that the temperature difference between the flue gas and the flue gas before and after heat exchange increased with the inlet temperature. At the same time, the water temperature difference remained unchanged. This paper analyzed the influence of different inlet temperatures and wind speed on heat transfer using the control variable method. It was found that the inlet temperature of flue gas was 190°C and the heat transfer efficiency was stable above 0.7 when the heat transfer was maximum, which was higher than the national standard. The irreversibility of the heat transfer process was analyzed by introducing the dimensionless equivalent thermal resistance R* and the thermal conductivity N*, which were derived from the dissipation number of the entransy. It was found that the heat exchanger operated stably when the flue gas temperature and the wind speed were constant. However, when the flue gas temperature or wind speed was increased, it was appropriate to use a lower wind speed to maintain the heat transfer performance before the temperature reached the critical temperature. After getting the critical temperature, the heat transfer performance was compared with the effective degree-NTU method and the effective degree-thermal conductivity method.

KEYWORDS:

• Air-water heat transfer
• micro heat pipe array
• entransy dissipation
• equivalent thermal resistance
• effective-thermal conductivity method

Nomenclature

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Acknowledgments

This study was supported by the Key research and development project in the social development field of science and technology department of Jilin Province: Performance research of flue gas heat recovery heat exchanger based on micro-heat pipe array in cold regions” (20200403135SF). Together with the Jilin provincial development and reform commission 2020 provincial budget capital construction fund (innovation capacity construction) project: technology research and development and application of composite capillary structure micro-heat pipe array in the field of heat exchange” (2020C027-3). Together with Project of Jilin Provincial Department of Education: “Research on heat transfer performance mechanism of micro heat pipe based on low temperature flue gas heat recovery heat exchanger” (JJKH20210264KJ). Together with the Key research and development project in the social development field of science and technology department of Jilin Province: “Research and demonstration of big data mining application of public building operation energy consumption based on BIM”(20190303059SF).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

Conceptualization: [Yang Jingang]; Methodology: [Wang Hao]; Formal analysis and investigation: [Wang Hao]; Writing - original draft preparation: [Wang Hao]; Writing - review and editing: [Wang Hao], [Yang Jingang], [Lv Jialu]; Funding acquisition: [Yang Jingang]; Resources: [Yang Jingang]; Supervision: [Yang Jingang], [Lv Jianlu].

Additional information

Funding

This work was supported by the Department of Science and Technology of Jilin Province [20200403135SF]; Education Department of Jilin Province [(JJKH20210264KJ]; Jilin Province Development and Reform Commission [2020C027-3]Department of Science and Technology of Jilin Province [20190303059SF].