Heat transfer mechanisms and their thermal performances need to be comprehensively studied in order to optimize efficiency and minimize energy losses.Different nanoparticles in the base fluid are investigated to upgra...Heat transfer mechanisms and their thermal performances need to be comprehensively studied in order to optimize efficiency and minimize energy losses.Different nanoparticles in the base fluid are investigated to upgrade the thermal performance of heat exchangers.In this numerical study,a finned shell and tube heat exchanger has been designed and different volume concentrations of nanofluid were tested to determine the effect of utilizing nanofluid on heat transfer.Fe_(2)O_(3)/water nanofluids with volume concentration of 1%,1.5% and 2% were utilized as heat transfer fluid in the heat exchanger and the obtained results were compared with pure water.ANSYS Fluent software as a CFD method was employed in order to simulate the mentioned problem.Numerical simulation results indicated the successful utilization of nanofluid in the heat exchanger.Also,increasing the ratio of Fe_(2)O_(3) nanoparticles caused more increment in thermal energy without important pressure drop.Moreover,it was revealed that the highest heat transfer rate enhancement of 19.1% can be obtained by using nanofluid Fe_(2)O_(3)/water with volume fraction of 2%.展开更多
The mechanism of pre roll ploughing for 3D fins on the outside surface of copper tube was studied systematically, and especially the process and conditions of 3D fin formation were analyzed. The right mathematical mod...The mechanism of pre roll ploughing for 3D fins on the outside surface of copper tube was studied systematically, and especially the process and conditions of 3D fin formation were analyzed. The right mathematical model was also established. Based on the volume of fin ploughed out is equal to the volume of the metal extruded up by the extruding face of the tool, the relations between fin height, pre roll ploughing feed and pre roll ploughing depth have been achieved. With the increase of pre roll ploughing depth which must be equal to groove depth, the fin height gradually becomes larger. There are different critical feeds with the various depths of pre roll ploughing. The pre roll ploughing feed is the critical one, the height of fin is largest. And when the feed is above the critical one, the fin height will reduce with the increase of feed. The theoretical analysis basically accords with experimental results.展开更多
This research investigates innovative fin-type radiators for automobile engine cooling system.Micro-channel and helical radiators,along with straight type,were analyzed for heat transfer characteristics under various ...This research investigates innovative fin-type radiators for automobile engine cooling system.Micro-channel and helical radiators,along with straight type,were analyzed for heat transfer characteristics under various conditions.The uniqueness of this study is evident in the design of microchannel and helical radiators.For helical radiators,the inner rod features 4/8 helical-shaped water galleries,while the outer tube frame with embedded fins remains consistent.In contrast,the microchannel radiators have compact trapezoidal-shaped water galleries with separate fin strips.Furthermore,the novelty of the research is enhanced by the utilization of 3D printing technology in the manufacturing process.In constant fin height analysis at varied water and air flow rate,Microchannel Water Air Radiator with fin height 10.5 mm(MCWAR10.5)depicted a higher heat transfer rate amongst the radiators.In comparison to Straight Water Air Radiator with fin height 9.5 mm(SWAR9.5),the heat transfer rate is 30.3%and 1.3 times higher.However,in constant fin surface area analysis,microchannel radiator(MCWAR3.2)illustrates lower heat dissipation than Helical radiator(HWAR138)but higher than HWAR134 and Straight radiator(SWAR6).The examination of pumping loss indicated that the Micro-channel radiator outperformed helical radiators due to its lower pressure loss.The average pressure loss for Micro-channel radiators was 0.74 kPa,making it 1.2 times higher than that of a straight radiator(0.62 kPa),indicating a better trade-off.展开更多
文摘Heat transfer mechanisms and their thermal performances need to be comprehensively studied in order to optimize efficiency and minimize energy losses.Different nanoparticles in the base fluid are investigated to upgrade the thermal performance of heat exchangers.In this numerical study,a finned shell and tube heat exchanger has been designed and different volume concentrations of nanofluid were tested to determine the effect of utilizing nanofluid on heat transfer.Fe_(2)O_(3)/water nanofluids with volume concentration of 1%,1.5% and 2% were utilized as heat transfer fluid in the heat exchanger and the obtained results were compared with pure water.ANSYS Fluent software as a CFD method was employed in order to simulate the mentioned problem.Numerical simulation results indicated the successful utilization of nanofluid in the heat exchanger.Also,increasing the ratio of Fe_(2)O_(3) nanoparticles caused more increment in thermal energy without important pressure drop.Moreover,it was revealed that the highest heat transfer rate enhancement of 19.1% can be obtained by using nanofluid Fe_(2)O_(3)/water with volume fraction of 2%.
文摘The mechanism of pre roll ploughing for 3D fins on the outside surface of copper tube was studied systematically, and especially the process and conditions of 3D fin formation were analyzed. The right mathematical model was also established. Based on the volume of fin ploughed out is equal to the volume of the metal extruded up by the extruding face of the tool, the relations between fin height, pre roll ploughing feed and pre roll ploughing depth have been achieved. With the increase of pre roll ploughing depth which must be equal to groove depth, the fin height gradually becomes larger. There are different critical feeds with the various depths of pre roll ploughing. The pre roll ploughing feed is the critical one, the height of fin is largest. And when the feed is above the critical one, the fin height will reduce with the increase of feed. The theoretical analysis basically accords with experimental results.
文摘This research investigates innovative fin-type radiators for automobile engine cooling system.Micro-channel and helical radiators,along with straight type,were analyzed for heat transfer characteristics under various conditions.The uniqueness of this study is evident in the design of microchannel and helical radiators.For helical radiators,the inner rod features 4/8 helical-shaped water galleries,while the outer tube frame with embedded fins remains consistent.In contrast,the microchannel radiators have compact trapezoidal-shaped water galleries with separate fin strips.Furthermore,the novelty of the research is enhanced by the utilization of 3D printing technology in the manufacturing process.In constant fin height analysis at varied water and air flow rate,Microchannel Water Air Radiator with fin height 10.5 mm(MCWAR10.5)depicted a higher heat transfer rate amongst the radiators.In comparison to Straight Water Air Radiator with fin height 9.5 mm(SWAR9.5),the heat transfer rate is 30.3%and 1.3 times higher.However,in constant fin surface area analysis,microchannel radiator(MCWAR3.2)illustrates lower heat dissipation than Helical radiator(HWAR138)but higher than HWAR134 and Straight radiator(SWAR6).The examination of pumping loss indicated that the Micro-channel radiator outperformed helical radiators due to its lower pressure loss.The average pressure loss for Micro-channel radiators was 0.74 kPa,making it 1.2 times higher than that of a straight radiator(0.62 kPa),indicating a better trade-off.
