Experimental Investigation of Heat Transfer and Pressure Drop in Square Metal Packed Duct with Different Boundary Heating

This paper presents experimental results of forced convection heat transfer and pressure drop across ( 12.5 * 12.5 * 100 cm ) square packed duct. The pad made of forty- eight metallic wrapping coil unit with (0.98 porosity ) and (26 W/m.°C thermal conductivity ). The local surface duct temperature and local heat transfer coefficient distribution, Nusselt number, pressure drop and friction factor were measured for heat flux (0.56 to 2.73 kW/m2) ,Reynolds number (40339 to 54797 ) and three boundary condition of heat flux imposed on duct surface . It was found that Nusselt number increases as Reynold number, heat flux and number of duct surface exposed to heat flux increases. Nusselt number in packed duct is to be ( 1.2 , 1.19 ) times higher than the empty ducts at heating all surface and top & bottom surface of packed duct respectively. Many empirical relation between Reynold number, Nusselt number and pressure drop obtained in this study

Effect of Solid Particle Properties on Heat Transfer and Pressure Drop in Packed Duct

This work examines numerically the effects of particle size, particle thermal conductivity and inlet velocity of forced convection heat transfer in uniformly heated packed duct. Four packing material (Aluminum, Alumina, Glass and Nylon) with range of thermal conductivity (from200 W/m.K for Aluminum to 0.23 W/m.K for Nylon), four particle diameters (1, 3, 5 and 7 cm), inlet velocity ( 0.07, 0.19 and 0.32 m/s) and constant heat flux ( 1000, 2000 and 3000 W/ m 2) were investigated. Results showed that heat transfer (average Nusselt number Nuav) increased with increasing packing conductivity; inlet velocity and heat flux, but decreased with increasing particle size.Also, Aluminum average Nusselt number is about (0.85,2.2 and 3.1 times) than Alumina, glass and Nylon respectively. From optimization between heat transfer and pressure drop through packed duct, it is found thatfinest ratio (Nuav / ?p) equal to (19.12) at (Dp = 7 cm, inlet velocity = 0.07 m/ s and 3000 W/m2 heat flux) with Aluminum as packing material

EXPERIMENTAL STUDY OF HEAT TRANSFER ENHANCEMENT IN HEAT EXCHANGER USING POROUS MEDIA

In present work experimental investigation of heat transfer enhancement in double pipe counter flow heat exchanger with insert metallic pad inner tube. Experimental work included the design of a tube in tube heat exchanger with the dimensions of (length 1.11m, 0.063m outer tube diameter and 0.031m inner tube diameter) Plain and saturated with pad heat exchanger . The examination were tested to evaluate their influence on effectiveness of heat exchanger, heat transfer coefficient, number transfer unit and pressure drop at steady-state condition. Water was used as a working fluid in the double pipe heat exchanger where hot water flow in inner tube and cold water flow in outer tube. The study was conducted at the hot water mass flow rates between (0.066-0.198 kg/s) and (0.1997 kg/s) cold water mass flow rate. The inlet temperatures of hot and cold water were (43 ᵒC) and (18 ᵒC) respectively. The results are obtained for range of Reynolds number to hot water (4862.9< Re<14633.8) and constant for cold water (Re=2912.2). The experimental results show that the major effective factors on the axial temperature distribution of heat exchanger, the effectiveness, heat transfer coefficient and pressure drop are the mass flow rate and adding metallic pad, where, The inner heat transfer coefficient of heat exchanger increased with increase in Reynold number, heat transfer coefficient when add metallic pad (WP) the inner tube of heat exchanger higher of plain pipe, the enhancement factor of heat transfer coefficient in metallic pad comparison with plain case are (2.074). The effectiveness decreases with increase hot water Reynold number, and increase by 26.5% when use of metallic pad compared with plain tube (WOP). The performance ratios obtained are in the ranges of 0.