Performance evaluation of a non-adiabatic capillary tube in a transcritical CO2 heat pump cycle

A study of transcritical carbon dioxide flow through diabatic capillary tubes

“…In spite of the growing use of capillary tubes in CO 2 -based refrigeration systems, very few related publications have been found in the open literature (Chen and Gu, 2005;Madsen et al, 2005;Cao and Yu, 2007;Agrawal and Bhattacharyya, 2008). These studies are limited by the lack of experimental data covering the typical operating conditions of light commercial refrigerating appliances, an important niche for CO 2 application.…”

“…However, the validation exercise was limited by the narrow range of geometries and operating conditions considered. More recently, Agrawal and Bhattacharyya (2008) proposed a numerical model for predicting the transcritical carbon dioxide capillary tube flow for heat pump applications. The results were compared with the numerical results of Chen and Gu (2005) and the experimental results of Madsen et al (2005), showing a good level of agreement.…”

Homogeneous versus separated two phase flow models: Adiabatic capillary tube flow in a transcritical CO2 heat pump

“…However, smaller systems could still employ a capillary tube for simplicity and inexpensiveness sacrificing pressure control to attain optimum discharge pressure. Recently Agrawal and Bhattacharyya [30,31] investigated the flow characteristics of an adiabatic and non-adiabatic capillary tube in a CO 2 transcritical heat pump cycle employing homogeneous two phase model, including tube geometry effects on system performance. Garcia-Valladares [32] numerically simulated the short tube orifice flow of transcritical carbon dioxide based on a one dimensional finite volume formulation under transient condition.…”

Computational investigations on heat transfer of turbulent supercritical CO2 in large tubes using RANS modelling

“…Within the range of turbine inlet temperature (550 − 700℃) that is of main interest to the CST power plants, higher cycle efficiency is achieved with sCO2 cycle than the supercritical steam and superheated steam cycles. Motivated by these superiorities brought about with sCO2 as working fluid, research on sCO2 power cycles have been fuelled recently [8][9][10][11][12][13][14].…”

“…Bruch et al [29] experimentally measured the heat transfer of turbulent sCO2 cooled in a vertical tube of = 6 mm. With buoyancy effect analysed, a new heat transfer correlation as the form of (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) has been formulated, where in Table 1-2 was employed and is:…”