Heat transfer coefficients were measured in a circular tube with dimpled surface. The almond type dimples were fabricated, the tube diameter (D) 19mm and dimple depth 3 mm ratio was kept constant, while holding diameter 10mm of dimple is required length 21.5mm because of the elongated shape. The Reynolds number based on the channel hydraulic diameter was varied from 25000to 95000. An experiment...

In this paper, the average heat transfer characteristics for a cross flow cylinder of 16 mm diameter in a vertical pipe has been studied for single-phase flow (water/oil) and multicomponent (non-boiling) flow (water-air, water-oil, oil-air and water-oil-air). The cylinder is uniformly heated by electrical heater placed at the centre of the element. The results show that the values of average he...

An experimental and numerical study of free convection heat transfer from a channel consisting of a vertical sinusoidal wavy surface and a vertical flat plate has been carried out. The vertical wavy surface was maintained at a constant temperature, while the flat plate is adiabatic. A Mach-Zehnder Interferometer was used to determine the local heat transfer coefficients of sinusoidal wavy surfa...

Slush nitrogen (SN(2)) is a mixture of solid nitrogen and liquid nitrogen, with an average temperature of -207 °C. To investigate whether plunging a French plastic straw (commonly used for sperm cryopreservation) in SN(2) substantially increases cooling rates with respect to liquid nitrogen (LN(2)), a numerical simulation of the heat conduction equation with convective boundary condition was us...

A heat pump system is constructed tO evaluate the performance and the heat transfer characteristics. Mixtures of R22/Rl42b are adopted in the heat pump. The heat transfer in the evaporator and the overall perfomance arc measured and analyzed in terms of the compositions and the flow rate of the refrigerants. The evaporator consists of counter~currem concentric circular tubes. Possibility of cap...

An experimental investigation is conducted to determine the effect of repeated-plate blockages of variable streamwise spacing on heat transfer characteristics of turbulent flow in rectangular ducts. The plates are attached to the upper and lower walls in a staggered arrangement. The experiments are carried out by mass transfer and the analogy between heat and mass transfer provides the necessar...