Numerical and experimental investigation of the heat transfer and the friction factor characteristics in a counter flow double pipe heat exchanger with and without Nano fluid was studied. Tests are ...performed for fully developed turbulent flow ranges, homogeneous Nano fluid. The double pipe heat exchanger consists of two tubes, the first inner plain tube has been manufactured from copper materials with inner and outer diameters of (11.2 and 12.7) mm respectively, the length of the first inner plain tube is 1057 mm. The second insulated an external tube which has been manufactured from PVC material with inner and outer diameters of (44.4 and 50)mm respectively, with a length is 1032mm. The flows have been tested at Reynolds number ranging (3019.43-4824.22). Nano particle size ranging (15-20)nm. The results show that the heat transfer rate increases as Reynolds number and volume concentration of Nano fluid increase. The increasing percentage of Nusselt number, friction factor and the performance factor of (15.72,11.51 and 11.57) % respectively for maximum volume concentration and volume flow rate of 3% and 1.6 lpm respectively. ANSYS FLUENT 2015 package was used to simulate the heat transfer and the fluid flow in the heat exchanger. The results show that the heat transfer increases when Nano fluid was added. The agreement was observed with experimental work with a maximum discrepancy of 12%.
The numerical investigation has been performed in this work to evaluate the performance of a triangular finned tube heat exchanger. In numerical work, the effect of space (2.5, 3 and 3.5 mm) distance ...between every two finned shaped and the volumetric flow rate on the heat transfer coefficient are examined consisting of cold water loop, hot air loop and the test section which is a concentric parallel flow double pipe heat exchanger. Coldwater and hot air are used as working fluids in the tube side and shell side, respectively. water at Reynold's numbers ranging from (3019.892 to 8035.044 ) flows through the inner tube. The inlet cold water temperatures are (45, 35, 25 and15) oC respectively. Numerical simulation has been carried out on the present heat exchangers to analyze both flow field and heat transfer using ANSYS, FLUENT15 computational fluid dynamic (CFD) package model. The finned tubes provide higher Nusselt numbers than the smooth tube. In the less pitch (p=2.5mm) compared with other pitches.
The heat transfer coefficient of steam condensation has a significant role in the performance of air-cooled heat exchangers. The purpose of this work is to predict the local/average local steam ...condensation heat transfer coefficient inside the horizontal flattened tube under vacuum conditions using numerous correlations that were developed by some researches which have been conducted under specified conditions. The results from these correlations have been compared with experimental data of Davies, therefore more investigate for the values are necessary to improve or/and validate the existing correlations. The effect of such parameters like the uniform heat flux and saturation temperature also have been studied on the local steam condensation heat transfer coefficient as the results show that the heat transfer coefficient decrease as the heat flux increase, while it increases as the steam saturated temperature increase.
Experimental and numerical investigations to study the effect of adding one slot to the impeller blades on the rotating stall and pressure fluctuations in a high-speed centrifugal blower. The ...experimental test rig includes a blower of the centrifugal, transducer of pressure as well measurement instrumentations which were constructed for this study. A data acquisition system (hardware) and its (software) have been developed to transfer the signal from the transducer of pressure to the computer then analysis with time. The experimental work has been implemented by measuring the static pressure variation as well fluctuating of pressure for two cases of impeller (without slot and with one slot). Static pressure has been taken in different points prepared on the front wall of the volute casing along one track for two cases of the impeller. This track is an angular track about the impeller. The results of the experiment show that the fluctuations of pressure increase with the mass flow rate decrease. Also, the results indicate that fluctuations of pressure decrease with adding slots into the impeller blades. The simulation of numerical has been carried out on blower of centrifugal into analysis both field of flow and fluctuations of pressure through using ANSYS (FLUENT 15). The simulation of numerical has been completed through solve the continuity and momentum equations with the moving reference framework technique inside the blower. The numerical simulation results show a good agreement with the results of the experiments.
A comparative study between two solutions which they usually work as a working pairs in pumpless absorption cooling system is achieved analytically with aid of ESS (Engineering Equation Solver) 9.43 ...software. The pump in this system is replaced by a vertical pipe (lift tube) to ensure the pressure difference between the condenser and the evaporator. These working pairs are Lithium Bromide-Water and Lithium Chloride-Water. The study intends Iraqi summer weather as an ambient circumstance. A thermodynamics model is designed to find the energy and Energy loss in each of system components. By solving the thermodynamic model, and assuming the same generator, absorber, condenser and evaporator temperatures in each case. It’s found that the system coefficient of performance is relatively the same while the probability of agglomeration in case of Lithium Bromide-Water system is higher because of the large salt concentration. It’s concluded that the Lithium Chloride-Water is most suitable in Iraqi circumstances in spite of high values of total energy loss which is obtained in case of Lithium Chloride-Water system if it is compared with the energy loss value in case of Lithium Bromide-Water system.
About 40% of the primary energy in the building sector is consumed for heating and cooling applications, where it started by relying on the use of sustainable energy sources through using an Earth ...tube heat exchanger (ETHE). ETHE is apparatus that works to transfer heat from ambient air to underground and vice versa which is used in heating and cooling applications. ETHE depends on undisturbed subsoil temperature, where the underground temperature doesn't change through the year at a certain depth. Ambient air passes through the buried heat exchanger in the ground and then cools down in summer and warms in winter. The good performance of this system depends on design efficiency. This paper reviews the experimental and numerical researches of ETHE which focuses on its design. The use of geothermal energy through ETHE leads to meeting energy demand and preserving the environment by reducing carbon dioxide emissions, which in turn affects the ozone.
The process of fluid movement is involved in a majority of food industries around the world. Viscous fluids are often used in such industries to make useful food products in bulk. These industries ...need to ensure that concerned equipment such as pipes are kept clean as well as are clear for the smooth transport of viscous liquids. The fluids are pumped in these pipes which results in friction over the walls of the pipe. Flow characteristics are the fundamental basis of the mass transfers taking place in food industries. The resulting qualities of the products are mainly reliant on these fluid flow properties. The design as well as control of the properties of a food in terms of its rheology is a big factor for the commercial success of a product. Therefore, to better understand this complex problem, it is crucial to first comprehend the rheological properties of different materials and fluids, which are widely present in the food industry. Thus, understanding the properties of fluids and overall the rheology of these is important. This paper discusses the fluid movements in food processing industries and discusses the concepts of fluids in motion. Concepts of viscosity and different flow regimes along with flow phenomena are also discussed in terms of rheology. Finally, as a case study example, the rheology of a complex fluid, honey, is reviewed in this paper.
In the current study, to enhance the characteristics and forced convection performance in the horizontal annular in the case of the presence of porous material and without porous material, energy ...analyses were performed. Many types of porous material, porosities, and diameters were used. Computational fluid dynamics was used to simulate an annuli tube in case of the presence of porous material and without porous material by utilization of ANSYS FLUENT software 17.2. The working fluid utilized was water with Reynolds number from 100-500 and constant wall heat flux at 150 kW/m2. Two types of porous media glass and steel balls, two different porosities (0.6 and 0.7), and two different porous material diameters (12 and 24mm) were utilized. Investigations occurred under the study state for studying heat transfer properties and flow of fluid in the annuli tube. The energy analysis outcomes showed that there is a relationship between Nu and Reynolds number. The highest enhancement of Nu number happened at 12mm diameter and 0.6 porosity for bolls of glass and 0.7 for bolls of steel. The pressure drop rising occurs with the rising of Re for all cases and the diameter of 12mm gives the maximum pressure drop for both steel and glass pellets and the uppermost pressure drop occurs at a porosity of 0.6. As compared with those in the annulus in the absence of a glass sphere as porous material at the same ball volumes.
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