Publications
Performance of Thermal Insulation of Different Composite Walls and Roofs Materials Used for Energy Efficient Building Construction in Iraq
Jan 7, 2024Journal Frontiers in Heat and Mass Transfer
Publisher The Science Press
DOI https://doi.org/10.32604/fhmt.2024.053770
Issue 4
Volume 22
This study numerically involves the performance of thermal insulation of different types of composite walls and roofs to demonstrate the best model that can be used for energy-efficient building construction in Iraq. The mathematical model is solved by building its code using the Transmission Matrix Method in MATLAB software. The weather data of 21st July 2022 in Baghdad City/Iraq is selected as a test day. The wall types are selected: the first type consists of cement mortar, brick, and gypsum, the second type consists of cement mortar, brick, gypsum, and plaster and the third type consists of cement mortar, brick, gypsum, air cavity, and sheathing timber. The roof types are chosen: the first type consists of reinforced concrete, gypsum, and plaster, and the second type consists of the precast concrete flag, river sand, tar, reinforced concrete, gypsum, and plaster. The obtained solutions are compared with previous studies for the same city but with different types of walls and roofs. The findings display that the second and third types of walls reduce the entry heat flux by 4% and 10% as compared to the first type of wall. Also, the results indicate that the second type of roof reduces the entry heat flux by 21% as compared to the firsttypeofroof.TheresultsconfirmthatthebestmodelsofwallsandroofsinIraqarethethirdandsecondtypes, respectively, as compared to other models and hence, the performance of insulation material strongly depends on the materials used while building them.
Performance of compound parabolic concentrator solar air flat plate collector using phase change material
Jan 3, 2024Journal Applied Thermal Engineering
Publisher Elsevier
DOI https://doi.org/10.1016/j.applthermaleng.2023.122224
Issue 1
Volume 240
This work involves an experimental investigation on two different new models of Compound Parabolic Concentrator (CPC) solar air flat plate collector with adding paraffin wax Phase Change Material (PCM). The first model is called involute shape model, whereas the second model is called normal shape model. To explore the best model performance, the structures of compound parabolic concentrator models have two symmetric giant parabolic mirror reflectors, similar concentration ratio of 1.7, similar flat plate receiver with 12 tubes filled by paraffin wax phase change material. The performances of both models are presented together for purpose of comparison. The tests have been performed in April and May 2023 in Mosul city/Iraq under standard conditions for around 11 h during the day. The outcomes indicated that rising in air mass flowrate leads to rise the receiver performance. The findings confirm that the thermal efficiency of normal shape is more efficient than involute shape by 7.6%, 13%, and 11.7% for 0.0085 kg/s, 0.0174 kg/s, and 0.027 kg/s, respectively. The optimum thermal performances for involute and normal shapes have been obtained equal 65.4% and 77.1% for 0.027 kg/ s, respectively. For constant air flowrate, the performance of normal shape is higher than involute shape by 15.5% (14th May), 12.6% (27th April) and 11.8% (15th April). A significant temperature change has been found in involute shape as compared to normal shape. The outlet temperature of normal shape is always lower than the involute shape for all air mass flowrate. It is demonstrated that phase change material and the position of the receiver have considerable influence on the model performance. The current work provides an important in formation for evaluating the compound parabolic concentrator model performance for Mosul/city.
SIMULATION AND INVESTIGATION OF NANO-REFRIGERANT FLUID CHARACTERISTICS WITH THE TWO-PHASE FLOW IN MICROCHANNEL
May 6, 2021Journal Frontiers in Heat and Mass Transfer
Publisher The Science Press
DOI https://doi.org/10.5098/hmt.17.21
Issue 1
Volume 17
This paper presents a simulation and investigation of the heat transfer coefficient, pressure drop, and thermal conductivity of two - phase flow. The simulation was performed of mixtures (Al2O3 nanoparticles with R134a refrigerant). The size of nanoparticles (Al2O3) which is used in this study is 30 nm and volume concentrations are 0.015 and 0.03. The two – phase flowing through a horizontal circular microchannel of (diameter 100 µm, and length 20 mm) under constant heat flux (3000 W/m2) and constant wall temperature (330 K), also in this study used the inlet temperature at -20 oC and mass flow rates are 0.3, 0.4, 0.5, 0.6, 0.7 and 0.8 g/s using in the dissipation of heat from electronic circuits by evaporation. The simulation is achieved by CFD numerical model using FLUENT ANSYS version 15 software. The results indicate the best temperature, pressure drop, density and volume fraction for two-phase flow Nano refrigerant in the microchannel. The higher heat transfer coefficient and pressure drop of two-phase Nano refrigerant flow at a high volume concentration (0.03) of Al2O3 when the mass flow rate is maximum. Finally, compared heat transfer coefficient of this study with the results of Kumar et al. (2013) at variation the mass flow rate, and found the root mean square of error (10%), also compared heat transfer coefficient of this study with results of Hernández et al. (2016) at variable volume concentration of nanoparticles Al2O3, and found the root mean square of error (3.7%).
NUMERICAL INVESTIGATION OF NUSSELT NUMBER FOR NANOFLUIDS FLOW IN AN INCLINED CYLINDER
Jan 20, 2021Journal Frontiers in Heat and Mass Transfer
Publisher The Science Press
DOI https://doi.org/10.5098/hmt.16.20
Issue 16
Volume 20
Numerical investigation is performed for the determination of Nusselt number of ZnO, TiO2 and SiO2 nanoparticles dispersed in 60% ethylene glycol and 40% water inside inclined cylinder for adiabatic and isothermal process. The present study was conducted for both the constant heat flux (10,000 W/m2) and constant wall temperature (313.15 K) boundary conditions. At the inlet, the uniform axial velocity and initial temperature (293 K) were assumed. The results show the change of average Nusselt number at Reynolds number (400), Rayleigh number (106) and volume fraction percentage (2%). From results for adiabatic process when increasing the slop up to (45o), the Nusselt number augments, while Nusselt number is reduced by further tube inclination. As it is clearly seen, the highest value of Nusselt number is corresponded to (45o) and for isothermal process it is shown that the value of Nusselt number in horizontal position is higher than the vertical position. The values of Nusselt number ratio were evaluated to be (45%, 31%, 25%) for the three Nano fluids (ZnO, TiO2 and SiO2) respectively, with the insulation (adiabatic) and (36%, 27%, 22%) without insulation (isothermal).
Effect of suction or blowing on velocity and temperature distribution of f low over a flat plate
Jan 12, 2021Journal Materials Today: Proceedings
Publisher Elsevier
DOI https://doi.org/10.1016/j.matpr.2020.12.735
Issue 42
Volume 2214 - 7853
In this paper, laminar, incompressible flow with constant pressure gradient and constant wall tempera ture over a flat plate for several values of fluid suction and blowing parameters at b = 0.1978, m = 0.09 and b=0.66, m=0.5 respectively were studied numerically. The governing nonlinear partial differential equations are transformed to ordinary differential equations by using a similarity variable and then solved numerically adopting Runge–Kutta integration method. Effects of continuous suction and blowing with very low ratio of constant velocity to free stream neglecting the mass transfer on the velocity, tem perature profiles and skin friction are presented. The results indicated that the skin friction factor is increased with increase the value of the suction for given Reynolds number. In order to reduce the skin friction, the laminar flow and avoid transition the blowing have been applied. The effect of fluid blowing parameter on velocity profile in hydrodynamic boundary layer are the certain incidence angles. Results show that the hydrodynamic boundary layer thickness is increased due to the blowing. It can be noted that the delaying separation is led to increase of the maximum lift. It was observed that increasing the maximum lift by maintain laminar flow to avoid transition and delaying separation to reduce skin friction is existing by suitable magnitude of suction or blowing. It is concluded that the skin friction is decreasing due to apply the blowing over a flat plate.
Numerical Analysis of Standard - Unstandard Gears for an External Gear Pumps
Jan 1, 2021Journal International Journal of Fluid Machinery and Systems
Publisher Turbomachinery Society of Japan
DOI http://dx.doi.org/10.5293/IJFMS.2021.14.1.025
Issue 1
Volume 1882-9554
The most widely of hydraulic applications power employed source that including low manufacturing costs and good performance are defined as the external gear pumps. In this study, the using of unstandard gears and influence on the performance of gear pumps are studied. These influences include pulsation factor of flow rate, flow rate of pump and trapped volume between two meshing gears. Matlab software has been used to evaluate performance by modifying algorithm and deriving the equations of pump flow rate. The unstandard gear is used in the study undertaken with +0.3 Rack shift coefficient. Results indicated the using of unstandard gears increase flow rate and reduce the trapped volume and pulsation flow rate factor. It was concluded that the factor of pulsation flow rate reduces as increase of teeth number which leads to pulsation flow rate stabilization.