An analytical approach to heat transfer and thermal distortions in non-contacting face seals

2017

EPJ Web Conf.

Abstract. This paper discusses test results concerning flow boiling heat transfer in a minichannel 1.7 mm in depth, 16 mm in width and 180 mm in length. The essential part of the experimental stand was a vertically oriented rectangular minichannel, which was heated asymmetrically with a plate made of Haynes-230 alloy. Distilled water was used as the cooling fluid. Changes in the temperature on the outer side of the heated plate in the central, axially symmetric part of the channel were measured using infrared thermography. Simultaneously, the other side of the heated plate in contact with the fluid was observed through a glass pane to identify the two-phase flow patterns. The one-dimensional model used for the heat transfer analysis took into account the heat flow direction, which was perpendicular to the direction of the fluid flow in the minichannel. The study involved determining local values of the heat transfer coefficient and generating boiling curves. The data for water were compared with the findings reported for the FC-72 fluid.

Section: Results and Analysismentioning

confidence: 99%

“…The use of microstructured surfaces produced in thermal processes (as described in [12][13][14][15]) is known to intensify the heat transfer process. Studies have been conducted on pool boiling [16][17][18][19][20], flow boiling [9][10][11][21][22][23] heat transfer and confined spaces as face seals [24][25].…”

Section: Introductionmentioning

confidence: 99%

Boiling heat transfer during flow of distilled water in an asymmetrically heated rectangular minichannel

Strąk

2017

EPJ Web Conf.

“…The data and image acquisition system consists of: an infrared camera (11) and a fast camera (10), a lighting system (9), a data acquisition station (12) and a computer with specialized software (13). The supply and control system consists of a inverter welder (14), a shunt (15), an ammeter (16) and a voltmeter (17).…”

Section: Experimental Standmentioning

confidence: 99%

“…One of the solutions is the use of boiling phenomena, the other -using enhanced heated surfaces produced by different methods [1][2][3]. Studies have been conducted on pool boiling [4][5][6], flow boiling [7][8][9][10][11] heat transfer and confined spaces as face seals [12,13]. Primarily passive methods are being developed for use in porous coating applications and in metal surface mechanical processing [14,15].…”

Section: Introductionmentioning

confidence: 99%

Impact of Fe powder sintering and soldering in production of porous heating surface on flow boiling heat transfer in minichannels

Depczyński

Piasecki²,

et al. 2017

E3S Web Conf.

Abstract. This paper focuses on identification of the impact of porous heated surface on flow boiling heat transfer in a rectangular minichannel. The heated element for Fluorinert FC-72 was a thin plate made of Haynes-230. Infrared thermography was used to determine changes in the temperature on its outer smooth side. The porous surface in contact with the fluid in the minichannel was produced in two processes: sintering or soldering of Fe powder to the plate. The results were presented as relationships between the heat transfer coefficient and the distance from the minichannel inlet and as boiling curves. Results obtained for using a smooth heated plate at the saturated boiling region were also presented to compare. In the subcooled boiling region, at a higher heat flux, the heat transfer coefficient was slightly higher for the surface prepared via soldering. In the saturated boiling region, the local heat transfer coefficients obtained for the smooth plate surface were slightly higher than those achieved from the sintered plate surface. The porous structures formed have low thermal conductivity. This may induce noticeable thermal resistance at the diffusion bridges of the sintered structures, in particular within the saturated boiling region.

“…If the solution is coupled two physical problems, it is possible to calculate the stresses and displacements associated with the changes in temperature along the minichannel walls. The physical phenomena observed during heat transfer in the minichannel for the heated element [14,15] and the unheated element can be described by means of the two-dimensional Laplace equation in the following form:…”

Section: Numerical Calculationsmentioning

confidence: 99%

Numerical calculations of the thermal deformations of the rectangular minichannel walls

Błasiak

Musiał

2016

EPJ Web of Conferences

Abstract. This paper analyzes the thermal deformations of the walls of a rectangular minichannel. The distribution of temperature on the walls and the local coefficients of heat transfer between the heated wall and the boiling fluid were determined on the basis of the experimental data. The thermal deformations were examined for two vertical walls: a heated Hastelloy X plate and an unheated stainless steel plate. The heat conduction and displacement equations were solved numerically using Ansys Workbench software. The distributions of temperature and the thermal deformations of the walls were obtained by appropriately combining the software modules with the mathematical description of the physical phenomena occurring in the minichannel and introducing the boundary conditions and the experimental data. It was found that, for the predetermined thermal conditions and the assumed thicknesses of the minichannel walls, thermal deformations can be omitted from further analysis. However, it is important to note that, if the geometrical dimensions of the minichannel had been different, the difference in the temperature along the minichannel length would have resulted in changes in the minichannel shape, i.e. its local narrowing, a reduction in the heat transfer efficiency, and, finally, a local change in the fluid flow rate.