Quasi-stationary phase change heat transfer on a fin

Abstract

Abstract. The paper presents heat transfer research basing on a long fin with a circular cross-section. Its basis is welded to the pipe where the hot liquid paraffin, having a temperature of 70oC at the inflow, is pumped. The analyzed element is a recurrent part of a refrigeration's condenser, which is immersed in a paraffin. The temperature of the inflowing liquid is higher than the temperature of the melting process for paraffin, which allows the paraffin to liquify. The temperature at the basis of the rib changes and it is assumed that the heat transfer is quasi-stationary. On this basis the estimation of the mean value of heat transfer coefficient was conducted. The unsteady thermal field of the investigated system was registered with an infrared camera V50 produced by a Polish company Vigo System. This device is equipped with a microbolometric detector with 384 × 288 elements and the single pixel size 25 × 25 ȝm. Their thermal resolution is lower than 70 mK at a temperature of 30 o C. The camera operates at 7,5 ÷ 14 μm long-wave infrared radiation range. For a typical lens 35 mm the special resolution is 0.7 mrad. The result of the calculations is mean heat transfer coefficient for the considered time series. It is equal to 50 W m -2 K -1 and 47 W m -2 K -1 on the left and right side of the fin, respectively. The distance between the experimental data and the curve approximating the temperature distribution was assessed with the standard deviation, Sd = 0.04 K.

Identification of building environment problems

“…The considered lecture room was characterized by a high temperature and carbon dioxide level. Besides, there were many people in the room and cooling of each person was difficult -especially via evaporation, which is a very efficient mode of cooling [10,11,12,13,14,15]. Thus, the student might have experienced low thermal comfort, or even discomfort, which could have influenced their sensations as expressed in the questionnaires.…”

Harnessing Nanomaterials for Enhanced Energy Efficiency in Transpired Solar Collectors: A Review of Their Integration in Phase-Change Materials

“…The thermal behavior of TSC equipped with PCM-based thermal storage was studied experimentally, and the results show that the latent heat thermal storage contributes to increased stability of the outlet air temperature of the collector and also a slight increase in the overall efficiency of the system, a fact suggested by Orzechowski T. et al [47]. The use of PCM in solar collectors can increase the operating hours and thermal stability [3,48,49].…”

Boiling heat transfer on porous single layer brass meshes

“…Also a large augmentation of heat flux over the smooth reference surface was reported. It also needs to be added that meshes and various other kinds of porous coatings can also be very effective in enhancing heat transfer in the flow boiling modes -as shown, among others, by [11][12][13][14], and also in pool boiling on ribs [15][16][17][18][19].…”