Experimental Study of Natural Convection in a Closed Cavity (Static Type Domestic Fridge)

This work provides an analysis of the thermal flow and behavior of the (load-free) refrigerator compartment. The main goal was to compare the thermal behavior inside the refrigerator cavity to the freezer door (home refrigerator) effect and install a fan on the freezer door while neglecting the heat transmitted by thermal radiation. Moreover, the velocity distribution, temperature, and velocity path lines are theoretically studied. This was observed without affecting the shelves inside the cabinet and the egg and butter places on the refrigerator door as they were removed and the aluminum door replaced with a glass door. This study aims to expand our knowledge about the temperature and flow fields of this refrigerator model. Finally, the development of this work highlights the importance of numerical simulation in the search for improvements in the design of this refrigerator model, which may assist refrigerator manufacturers.

Droplet Heat Transfer on Micropost Arrays With Hydrophobic and Hydrophilic Characteristics

Heat transfer analysis for a water droplet on micropost arrays is carried out while mimicking the environmental conditions. Since the micropost arrays spacing size alters the state of the hydrophilicity of the surface, the size of the micropost arrays spacing is varied and the resulting heat transfer characteristics are analyzed. Spreading rate of water droplet on the micropost arrays is considered and the adhesion force for the pinning of the water droplet on the micropost arrays is presented. Temperature and flow fields are predicted and the predictions of flow velocity inside the water droplet are validated through the particle image velocimetry (PIV). The Nusselt number variation for various sizes of the micropost arrays is obtained for two droplet volumes. It is found that reducing the solid fraction of micropost array beyond ϕs = 0.25, the Cassie and Baxter state of the surface changes to the Wenzel state; in which case, hydrophobic characteristics changes to hydrophilic characteristics for the water droplet. Heat transfer from the droplet bottom gives rise to development of the buoyancy and the Marangoni currents, which in turn generate two counter rotating circulation cells. The center of circulation cells moves further in the droplet upper part for the hydrophobic droplet case. The Nusselt number attains high values for the hydrophobic droplet at micropost array spacing size b = 10 μm and hydrophobic droplet at spacing size b = 50 μm due to fin effects of the micropost arrays.

Modelling Methods of Magnetohydrodynamic Phenomena Occurring in a Channel of the Device Used to Wash out Spent Automotive Catalyst on Metallic Substrate by a Liquid Metal

The recovery of precious metals is necessary for environmental and economic reasons. Spent catalysts from automotive industry containing precious metals are very attractive recyclable material because as the devices. they have to be periodically renovated and eventually replaced. Among automotive catalysts withdrawn from use, these with metallic carrier constitute quite a big group. Metallic carriers are usually obtained from steel FeCrAl , which is covered by a layer of PGM acting as a catalyst. World literature describes a number of pyro-or hydrometallurgical methods used for recovery of platinum from used automobile catalytic converters. However, all methods, available in the literature, are used to recover platinum from ceramic carrier. This paper presents the new method of removing platinum from the spent catalytic converters applying lead as a collector metal in a device used to wash out platinum by using mangetohydrodynamic pump. The article includes the description of the methods used in modelling magnetohydrodynamic phenomena (coupled analysis of the electromagnetic, temperature and flow fields) occurring in this particular device for this kind of waste. The general phenomena and ways of coupling the various physical fields for this type of calculation have also been described. The basic computational techniques with a discussion of their advantages and disadvantages have been presented.

Modelling Methods of Magnetohydrodynamic Phenomena Occurring in a Channel of the Device Used to Wash Out the Spent Automotive Catalyst by a Liquid Metal

The recovery of precious metals is necessary for environmental and economic reasons. Spent catalysts from automotive industry containing precious metals are very attractive recyclable material as the devices have to be periodically renovated and eventually replaced. This paper presents the method of removing platinum from the spent catalytic converters applying lead as a collector metal in a device used to wash out by using mangetohydrodynamic stirrer. The article includes the description of the methods used for modeling of magnetohydrodynamic phenomena (coupled analysis of the electromagnetic, temperature and flow fields) occurring in this particular device. The paper describes the general phenomena and ways of coupling the various physical fields for this type of calculation. The basic computational techniques with a discussion of their advantages and disadvantages are presented.

Lattice Boltzmann Simulations on the Charging Procedure of a Solar Storage Tank With Immersed Phase Change Materials

The transient charging procedure of a rectangular solar storage tank with immersed tubes filled by phase change materials (PCM) have been simulated by a Lattice Boltzmann Method (LBM). The energy charge speeds for the storage tank with and without the PCM have been compared. The transient temperature and flow fields including melting of the PCM are also presented. The transient interfaces between fluid and solid are clearly shown. The enhancement of the energy storage capability due to the PCM is calculated based on the simulation results. Also the effects of the arrangement of the PCM are discussed.