Experimental study of a straight channel printed circuit heat exchanger on supercritical CO2 near the critical point with water cooling. (April 2020)

• Record Type: Journal Article
• Authors: Park, Joo Hyun; Kwon, Jin Gyu; Kim, Tae Ho; Kim, Moo Hwan; Cha, Jae-Eun; Jo, HangJin
• Is Part Of: International journal of heat and mass transfer. Volume 150(2020)
• Publication Date: 2020-04
• Subjects: Carbon dioxide (CO2) -- Brayton cycle -- Heat transfer -- Supercritical; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2020.119364
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Experiments of sCO2 integral loop were performed for straight PCHE. Heat transfer performance of CO2 was examined at the near critical point and far critical point. Discretization method for PCHE near the critical point of CO2 was investigated. Abstract: The study presents an experimental examination of heat transfer of straight printed circuit heat exchanger (PCHE) for a precooler of supercritical carbon dioxide (sCO2 ) Brayton cycle. To perform heat transfer experiment, experimental loop for thermal hydraulic of CO2 in supercritical (ETHICS) was constructed at POSTECH. The straight PCHE was independently manufactured by photochemical etching and diffusion bonding process. An experiment for CO2 cooling with water was conducted via the ETHICS. We focused on heat transfer and flow characteristics of CO2 in the printed circuit heat exchanger. The experiments were conducted at three operating conditions for CO2 cooling, namely the trans-critical case (cooling from supercritical state to subcooled liquid), near the critical case (cooling from gas-like supercritical state to liquid-like supercritical state), and far critical case (cooling just in gas-like supercritical state). Nusselt numbers for different pressure and different operating conditions were compared by following typical analysis used in previous which is using averaged enthalpy based on inlet and outlet data but we conclude that the method of average value using inlet and outlet data is not appropriate for data reduction due to significant changes in the properties of CO2 near the critical point. Instead of that, we propose to use discretization method in data reduction of experimental data of CO2 near the critical point. It is difficult to predict heat transfer performance near the critical point of CO2 in PCHE. Hence, the data from this experiments and discretization method for data reduction are useful in designing a precooler for the sCO2 Brayton cycle.