This paper presents the numerical study of the two-dimensional forced convection heat transfer across three in-line flat tubes confined in a channel the flow under incompressible, steady-state conditions. This system is solved in the body fitted coordinates (BFC) using the finite volume method (FVM). The constant temperature is imposed on the surface of the tubes as the thermal boundary conditions. The range of the longitudinal pitch-to-diameter ratio SL/Ds is considered of 2.0-4.0 and Reynolds numbers varies within the range of 25-300, and Prandtl number is taken as 0.7. The temperature contours, local Nusselt number distributions at the tube surface and mean Nusselt number were analyzed. The strength of the heat transfer between the surface of the tubes and the air flow increases with increasing Reynolds number and increasing pitch-to-diameter the ratio.

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A numerical study of forced convection heat transfer over a series of flat tubes between parallel plates

This paper presents an experimental investigation into the heat transfer and pressure drop characteristics of air flow in a staggered flat tube bank in crossflow with laminarforced convection. Measurements were conducted for sixteen tubes in the direction of 
flow and four tubes in rows. The air velocity varies between 0.6–1.0 m/s and the Reynolds number varied from 373 to 623. The total heat flux supplied in all tubes are changed from 967.92 to 3629.70 W/m2. The results indicate that the average Nusselt 
number for all the flat tubes increased by 11.46–46.42%, with the Reynolds numbers varying from 373 to 623 at the fixed heat flux. The average Nusselt number increased by 21.39–84%, and the total heat flux varyied between 967.92–3629.70 W/m2 with a 
constant Reynolds number Re = 498. In addition, the pressure drop decreased with an increase in the Reynolds number. A new mean Nusselt number-Reynolds number correlation was found, and the correlation yielded good predictions for the measured data with a confidence interval of 98.9%.

/pdf/experimental-investigation-on-heat-transfer-and-pressure-2d6z8rri7u.pdf

Experimental Investigation on Heat Transfer and Pressure Drop Characteristics of Air Flow over a Staggered Flat Tube Bank in Crossflow

An experimental study has been made to investigate heat transfer and air flow around flat tube of in-line flat tube banks with laminar forced convection. Measurements were conducted for sixteen tubes in the flow direction;four tubes in the rows, the three air velocity (0.6, 0.8 and 1.0 ms-1) and Reynolds number are ReDh = 527, 703 and 880,where Dh isthe hydraulic diameter of the tube. The total heat flux supplies in all tubes are 967.92, 2258.48 and 3629.70 Wm-2, respectively. The study results indicate that the average Nusselt number of all flat tubes has increased 23.7%-36.7% with Reynolds numbers varying from 527 to 880 at the fixed heat flux; also averageNusselt number has increased11.78% - 23.75% at the heat flux are varying 967.92, 2258.48 and 3629.70 Wm-2, respectively at the Reynolds number Re = 703. In addition, the pressure drop decreaseswith the increase of Reynolds number. The Nusselt number-Reynolds number correlation was found to be 2 1 C Nu  C Re , the correlation yielded good predictions of the measured data with the mean error R2 = 0.992.

/pdf/an-experimental-study-of-air-flow-and-heat-transfer-over-in-3yug771u17.pdf

An Experimental Study of Air Flow and Heat Transfer Over In-Line Flat Tube Bank

This paper aims to predict the heat transfer and pressure drop for an in-line flat tubes configuration in a cross-flow using an artiﬁcial neural network. The numerical study of a two-dimensional steady state and incompressible laminar flow for an in-line flat tube configuration in a cross-flow is also considered in this study. The Reynolds number varies from 10 to 320. Heat transfer coefficient and pressure drop results are presented for tube configurations at three transverse pitches of 2.5, 3.0, and 4.5 with two longitudinal pitches of 3.0 and 6.0. The predicted results for the average Nusselt number and dimensionless pressure show good agreement with previous work. The accuracy between the actual values and the neural network approach model results was obtained with a mean absolute relative error less than 4.1%, 4.8%, and 3.8% for the average Nusselt number, dimensionless pressure drop and average friction factor, respectively.

/pdf/heat-transfer-and-pressure-drop-prediction-in-an-in-line-2d0hg7p9s4.pdf

Heat Transfer and Pressure Drop Prediction In An In-Line Flat Tube Bundle by Radial Basis Function Network

Integration of emerging PCMs and nano-enhanced PCMs with different solar water heating systems for sustainable energy future: A systematic review

The most popular renewable energy source is solar energy, which characterises as free, clean, and environmentally friendly. Photovoltaics (PV) generate electricity from daylight, becoming increasingly popular in residential and other applications. The potential energy delivery from a photovoltaic module is a function of solar radiation falling on the front surface and module operating temperature. However, these systems are modified to improve energy generation by placing an absorber on the bottom side of the module termed a Photovoltaic Thermal (PVT) system to reduce module temperature. The current study aims to investigate the experimental heat transfer efficiency for the fabricated PVT system employing two-sided serpentine flow thermal absorber and phase change material (PCM). PCM discharge the latent heat during off-sunshine hours to provide additional hot water. The experiment setup was tested with water as a working fluid in the flow rate range of 0.0085–0.067 kg/s. The optimal flow rate at which maximum heat gain of 757 W was obtained 0.033 kg/s with an average energy-saving efficiency of 69 %. The results confirm enhanced energy delivery of 3–5 % by PVT-PCM system compared to reference PV module for the same ambient operating conditions. Furthermore, the study reveals that overall efficiency of the PVT setup augment with the use of a thermal absorber and PCM, while the thermal efficiency is a factor that depends on the working fluid properties. • Fabrication of a two-side serpentine flow absorber for cooling photovoltaic thermal-phase change material collector system. • Results from heat transfer analysis lead to higher heat removal at 0.033 kg/s fluid flow rate of water. • Overall and energy-saving efficiency enhance by 23% and 28% for water flow rate of 0.033 kg/s as compared to other flow rates. • As the water flow rate increases from 0.0085 kg/s to 0.033 kg/s, the panel maximum average power output gains by 3%. 

Thermal analysis of hybrid photovoltaic-thermal water collector modified with latent heat thermal energy storage and two side serpentine absorber design

Experiments have been conducted to study the effect of mass flow rate on heat and mass transfer coefficients in a packed bed. It has been observed that an increase in mass flow rate of water increases the heat and mass transfer coefficients by 1.7–1.9 and 3.2–3.8 times, respectively, at 55–95 °C. The diffusion of oxygen from packed bed inlet water, obtained from experimental data, can be used to estimate the mass transfer coefficients. The theoretical equation available in literature is compared and satisfactory agreement has been observed. The increase in inlet water temperature decreases both the heat and
mass transfer coefficients by 60% and 25%, respectively, because of the reduced driving force. The increase in oxygen concentration in inlet water has no significant effect on either heat or mass transfer coefficients.

/pdf/experimental-analysis-of-heat-and-mass-transfer-in-a-packed-1wu42ql1m8.pdf

D. M. Reddy Prasad

Papers

Thermal analysis of hybrid photovoltaic-thermal water collector modified with latent heat thermal energy storage and two side serpentine absorber design

Experimental analysis of heat and mass transfer in a packed bed