In most domestic and commercial refrigeration systems, frost forms on the air-side surface of the air-to-refrigerant heat exchanger. Frost-tolerant designs typically employ a large fin spacing in order to delay the need for a defrost cycle. Unfortunately, this approach does not allow for a very high air-side heat transfer coefficient, and the performance of these heat exchangers is often air-si...

in order to examine the laminar convective heat transfer of nanofluid, experiments carried out using silver-oil nanofluid in a concentric annulus with outer constant heat flux as boundary condition. silver-oil nanofluid prepared by electrical explosion of wire technique and observed no nanoparticles agglomeration during nanofluid preparation process and carried out experiments. the average size...

Original scientific paper In this paper, the results of investigations of the temperature field distribution and tool wearing during C60 steel turning are presented. Abrasive wear resistance tests were carried out for cutters made of low-alloy high-speed steel. Steel samples were heat treated, and then were subjected to ion nitriding, TiN coating, or to complex treatment. The influence of cutti...

In this paper, three-dimensional incompressible laminar fluid flow in a rectangular microchannel heat sink (MCHS) using Al2O3/water nanofluid as a cooling fluid is numerically studied. CFD prediction of fluid flow and forced convection heat transfer properties of nanofluid using single-phase and two-phase model (Eulerian-Eulerian approach) are compared. Hydraulic and thermal performance of microch...

Engineering MEMS devices using finite element analysis can be very rewarding, provided the analysis is valid, i.e. it accurately simulates reality throughout the desired range of input and resultant imposition upon dependent physical properties and behavior. With respect to FEM’s use in MEMS, it is can be very useful. Doped single crystal silicon is a substance whose material and physical prope...

As LED applications continue to expand beyond lighting and sensors, the power levels and heat dissipation requirements will also continue to increase. Thermal management is becoming a major design issue for highpower LED systems. The size and weight of conventional bulk metal heat sinks cannot satisfy shrinking packaging constraints. Active cooling methods, such as forced air cooling or even pu...

In this paper, the heat transfer performances of aluminum metal foams, placed on horizontal plane surface, was evaluated in forced convection conditions. Three different types of contacts between the sample and the heated base plate have been investigated: simple contact, brazed contact and grease paste contact. First, in order to perform the study, an ad hoc experimental set-up was built. Seco...

The influence of the growth temperature and the pH of the heating medium on the heat resistance at different temperatures of Salmonella typhimurium ATCC 13311 was studied and described mathematically. The shift of the growth temperature from 10 to 37 degrees C increased heat resistance of S. typhimurium fourfold. The pH of the heating medium at which heat resistance was maximum was pH 6 for cel...

This paper reports on the dissipation of heat generated by a high power LED array using piezoelectric fans. Both numerical and experimental studies were carried out to evaluate the heat dissipation efficiency of high power LED package operating under multiple vibrating fans. Two vibrating fans were vertically oriented to the LED package and arranged according to configuration A (for edge to edg...

abstract: in this paper, a new population-based search called the bees algorithm (ba) is presented to estimate the time-dependent heat transfer coefficient and the corresponding heat flux at the boundaries of a two-dimensional body subjected to transient heat conduction, using the temperature measurements at discrete nodal locations on the boundaries, where heat flux is specified as the boundar...