Development of a Modified Magnetic Moulding Set up for Improved Heat Transfer

2020 ◽  
pp. 611-617
Author(s):  
B. Anand Ronald ◽  
M. Harshal ◽  
K. Barath Varadaraj ◽  
G. Gopinath
Keyword(s):  
Heat Transfer ◽  
Set Up

scholarly journals Modification of a Solar Thermal Collector to Promote Heat Transfer inside an Evacuated Tube Solar Thermal Absorber

2021 ◽  
Vol 11 (9) ◽  
pp. 4100
Author(s):  
Rasa Supankanok ◽  
Sukanpirom Sriwong ◽  
Phisan Ponpo ◽  
Wei Wu ◽  
Walairat Chandra-ambhorn ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Small Scale ◽  
Medium Temperature ◽  
Change Behavior ◽  
Set Up ◽  
Evacuated Tube ◽  
Heating Medium

Evacuated-tube solar collector (ETSC) is developed to achieve high heating medium temperature. Heat transfer fluid contained inside a copper heat pipe directly affects the heating medium temperature. A 10 mol% of ethylene-glycol in water is the heat transfer fluid in this system. The purpose of this study is to modify inner structure of the evacuated tube for promoting heat transfer through aluminum fin to the copper heat pipe by inserting stainless-steel scrubbers in the evacuated tube to increase heat conduction surface area. The experiment is set up to measure the temperature of heat transfer fluid at a heat pipe tip which is a heat exchange area between heat transfer fluid and heating medium. The vapor/ liquid equilibrium (VLE) theory is applied to investigate phase change behavior of the heat transfer fluid. Mathematical model validated with 6 experimental results is set up to investigate the performance of ETSC system and evaluate the feasibility of applying the modified ETSC in small-scale industries. The results indicate that the average temperature of heat transfer fluid in a modified tube increased to 160.32 °C which is higher than a standard tube by approximately 22 °C leading to the increase in its efficiency by 34.96%.

Experimental and numerical investigations on a high-density polyethylene (HDPE) blown film cooling with a new design of the counter-flow/radial jet air-ring

2021 ◽  
pp. 875608792110260
Author(s):  
ME Ismail ◽  
MM Awad ◽  
AM Hamed ◽  
MY Abdelaal ◽  
EB Zeidan
Keyword(s):  
Heat Transfer ◽  
Numerical Simulations ◽  
Film Cooling ◽  
Radiation Heat Transfer ◽  
Absolute Error ◽  
Numerical Results ◽  
Upper Lip ◽  
Original Design ◽  
Blown Film ◽  
Set Up

This study experimentally and numerically investigates a typical HDPE blown film production process cooled via a single-lip air-ring. The processing observations are considered for the proposed subsequent modifications on the air-ring design and the location relative to the die to generate a radial jet, directly impinging on the bubble. Measurements are performed to collect the actual operating parameters to set up the numerical simulations. The radiation heat transfer and the polymer phase change are considered in the numerical simulations. The velocity profile at the air-ring upper-lip is measured via a five-hole Pitot tube to compare with the numerical results. The comparison between the measurements and the numerical results showed that the simulations with the STD [Formula: see text] turbulence model are more accurate with a minimum relative absolute error (RAE) of 1.6%. The numerical results indicate that the peak Heat Transfer Coefficient (HTC) at the impingement point for the modified design with radial jet and longer upper-lip is 29.1% higher than the original design at the same conditions. Besides, increasing the air-ring upper-lip height increased the averaged HTC, which is 13.4% higher than the original design.

scholarly journals HOT WIRE METHOD FOR THE THERMAL CHARACTERIZATION OF MATERIALS: INVERSE PROBLEM APPLICATION

2003 ◽  
Vol 2 (2) ◽  
Author(s):  
S. André ◽  
B. Rémy ◽  
F. R. Pereira ◽  
N. Cella ◽  
A. J. Silva Neto
Keyword(s):  
Heat Transfer ◽  
Thermal Characterization ◽  
Hot Wire ◽  
Confidence Bounds ◽  
Linear Temperature ◽  
Direct Model ◽  
Electrical Analogy ◽  
Wire Method ◽  
Characterization Of Materials ◽  
Set Up

An experimental set-up of the hot wire method is presented. The present design allows the measurement of the temperatures at two different points on the heating wire with an acquisition system that performs measurements at a frequency of 1kHz with a 12 bit numerical converter. An analytical solution for the direct model for the time dependent problem of heat transfer is employed. It is based on the quadrupole method which basically consists in a transfer matrix approach which is possible through the use of Laplace transforms. It extends the electrical analogy of heat transfer problems using the notion of impedance, and allows to take into account the thermal behavior of the wire, as well as contact resistance and heat loss effects in a very simple straightforward way. In the identification process carried on the temperature experimental data relies on a sampling of the data that is logarithmically spaced in time. The initial guesses for the thermal conductivity values are obtained applying the well known and ideal model of the linear temperature evolution versus the logarithm of the time. These values are used to start up the algorithms that are applied in the minimization of the cost functional of the squared residues between measured and calculated temperatures. The precision of the estimates is assessed with the calculated confidence bounds obtained by the variance-covariance matrix at the converged solution.

Design of a Thermostat for Precise Temperature Control From −190 Deg to +650 Deg C

1969 ◽  
Vol 91 (2) ◽  
pp. 168-172
Author(s):  
J. Ansari ◽  
W. Leidenfrost ◽  
R. Oldenburger
Keyword(s):  
Heat Transfer ◽  
Differential Equations ◽  
Temperature Control ◽  
Hypothetical Case ◽  
Heat Transfer Medium ◽  
System Parameters ◽  
Set Up ◽  
Proportional Controller ◽  
Cylindrical Block ◽  
Selection Of

A proposed apparatus for controlling temperatures from −190 deg to +650 deg with an estimated accuracy of 0.001 deg C is described. The apparatus utilizes helium as the heat transfer medium. The selection of the gain constants of the controller depends upon the system parameters. The hypothetical case of a solid cylindrical block with an integral plus proportional controller is considered, the differential equations are set up, and a graphical scheme is presented for the selection of the controller constants.

Study of Electrostatic-Induced Jumping Droplets on Superhydrophobic Surfaces

2017 ◽  
Author(s):  
B. Traipattanakul ◽  
C. Y. Tso ◽  
Christopher Y. H. Chao
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Electrostatic Force ◽  
Droplet Radius ◽  
Inertia Force ◽  
Resistance Force ◽  
Average Charge ◽  
Electrical Voltage ◽  
Fluid Systems ◽  
Set Up

Condensation of water vapor is an important process utilized in energy/thermal/fluid systems. When droplets coalesce on the non-wetting surface, excess surface energy converts to kinetic energy leading to self-propelled jumping of merged droplets. This coalescing-jumping-droplet condensation can better enhance heat transfer compared to classical dropwise condensation and filmwise condensation. However, the resistance force can cause droplets to return to the surface. These returning droplets can either coalesce with neighboring droplets and jump again, or adhere to the surface. As time passes, these adhering droplets can become larger leading to progressive flooding on the surface, limiting heat transfer performance. However, an electric field is known to be one of the effective methods to prevent droplet return and to address the progressive flooding issue. Therefore, in this study, an experiment is set up to investigate the effects of applied electrical voltages between two parallel copper plates on the jumping height with respect to the droplet radius and to determine the average charge of coalescing-jumping-droplets. Moreover, the gravitational force, the drag force, the inertia force and the electrostatic force as a function of the droplet radius are also discussed. The gap width of 7.5 mm and the electrical voltages of 50 V, 100 V and 150 V are experimentally investigated. Droplet motions are captured with a high-speed camera and analyzed in sequential frames. The results of the study show that the applied electrical voltage between the two plates can reduce the resistance force due to the droplet’s inertia and can increase the effects of the electrostatic force. This results in greater jumping heights and the jumping phenomenon of some bigger-sized droplets. With the same droplet radius, the greater the applied electrical voltage, the higher the coalescing droplet can jump. This work can be utilized in several applications such as self-cleaning, thermal diodes, anti-icing and condensation heat transfer enhancement.

scholarly journals Air-impingement freezing of peeled shrimp: Analysis of flow field, heat transfer, and freezing time

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401983504 ◽  
Author(s):  
Dazhang Yang ◽  
Jing Xie ◽  
Wan Tang ◽  
Jinfeng Wang ◽  
Zhitao Shu
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Flow Field ◽  
Jet Flows ◽  
Freezing Process ◽  
Freezing Time ◽  
Air Jet ◽  
Food Freezing ◽  
Air Impingement ◽  
Set Up

The air-impingement freezing technique is a fast and efficient freezing method, which is widely used in food freezing and electronic industry. A novel air-impingement freezing machine was set up to investigate the food freeze. The freezing process of peeled shrimps by air-impingement freezing technique was studied experimentally and numerically. The freezing time of shrimp (150 count/lb) from +11°C to −18°C was about 100–140 s. The flow field and temperature distribution of peeled shrimp were studied by the solidification and melting model in FLUENT 6.3. The results show that the air jet flows away from the surface of the shrimp after the separation points so that the flow field and heat transfer were bad in the separation resign. In addition, the food freezing time of natural convection and air-impingement was compared, and the result shows that the air-impingement freezing time is about one-tenth than the natural convection freezing in freezer. In order to optimize the air-impingement freezing, H/D’s value was adjusted in the range of 4–8. The result indicates that the freezing time was increasing with the increase in H/D value, and H/D was recommended to be 6 in the impingement freezing.

scholarly journals Optimizing air velocity for the underfloor forced ventilation to protect a refrigerated warehouse from frost heaving

2018 ◽  
Vol 38 (3) ◽  
pp. 321-327
Author(s):  
Jingfu Jia ◽  
Manjin Hao ◽  
Jianhua Zhao
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Frost Heave ◽  
Forced Ventilation ◽  
Air Velocity ◽  
Set Up

Forced or natural ventilation is the most common measure of frost heave protection for refrigerated warehouse floor. To optimize air velocity for the underfloor forced ventilation system of refrigerated warehouse, a steady state three-dimensional mathematical model of heat transfer is set up in this paper. The temperature fields of this system are simulated and calculated by CFD software PHOENICS under different air velocity, 1.5m/s, 2.5m/s or 3.5m/s. The results show that the optimized air velocity is 1.5m/s when the tube spacing is 1.5m.

Experimental Study of the Temperature Field Equation in the Leeward Tunnel during Mine Fire Period

2012 ◽  
Vol 588-589 ◽  
pp. 1842-1848
Author(s):  
Wen Cai Wang ◽  
Yu Hong Jiang ◽  
Tao Hou ◽  
Wei Liu ◽  
Yang Lu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Temperature Field ◽  
Field Equation ◽  
Wind Speed ◽  
Stable Phase ◽  
Measuring Point ◽  
Mine Fire ◽  
Mine Roadway ◽  
Set Up

According to the principle of heat transfer, the temperature field equation in the leeward tunnel was set up and the experimental device with a ratio of 1:20 was built. When it happened to fire in roadway, the correctness of the temperature field equation can be verified by the experiment. In experiments, the armored thermocouple and color paperless recorder were used to record the temperature of each measuring point. The S-3-300 pitot tube and YJB-2500 compensation micro-manometer were used to determine the wind speed. When the mine roadway fired, the experiment determined the temperature field equation experiment coefficient of Kc. It showed that in the developing phase of the fire Kc= 15 ~ 20, in the stable phase of the fire Kc= 10 ~ 15, in the failing phase of the fire Kc= 20 ~ 25.

Effects of pH and surfactant on the forced convection of Al2O3/water and TiO2/water nanofluids

2020 ◽  
pp. 1-18
Author(s):  
Deepak Khurana ◽  
Sudhakar Subudhi
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Particle Concentration ◽  
Sodium Dodecyl ◽  
Suspension Stability ◽  
Heat Transfer Characteristics ◽  
Maximum Enhancement ◽  
Effects Of Ph ◽  
Set Up ◽  
The Stability

Abstract The present paper deals with the forced convection of Al2O3/water and TiO2/water nanofluids with the variation of pH and addition of surfactant in nanofluids. The aim of this study is to investigate the effect of suspension stability on the heat transfer and pressure drop characteristics of nanofluids. The present experimental set up is same as used by our earlier paper [1]. The suspension stability of nanofluids is improved by varying pH of nanofluids. The pH in this study is varied from 3.5±0.2 to 12.5±0.2. Addition of surfactants is employed to improve the suspension stability of nanofluids. The SDS (sodium dodecyl sulfate) surfactant of 0.05 wt % is used to increase the stability of nanofluids in the present study. It is observed that by increasing the suspension stability with the variation of pH and addition of surfactant, the heat transfer characteristics have improved appreciably. The maximum enhancement in heat transfer is obtained with TiO2/water nanofluids at a particle concentration of 0.1 vol % and a pH of 3.5±0.2.

Dynamic Performance of Conventional and Electrically Activated Engine Thermostats

2001 ◽  
Author(s):  
L. Alan Gunter ◽  
M. Razi Nalim
Keyword(s):  
Heat Transfer ◽  
Dynamic Performance ◽  
Control Device ◽  
The Road ◽  
Engine Control System ◽  
Passive Devices ◽  
Heating Device ◽  
Set Up ◽  
Spool Valve ◽  
Engine Coolant

Abstract This study concerns the dynamic performance of passive and active wax-actuator driven thermostats. The study is extended to wax actuator driven thermostats that have been fitted with a heating device, such that the thermostat can be actuated electrically. The thermostat valve type chosen for this study is a balanced, sleeve-type thermostat typically used in large over-the-road and industrial diesel engines. The valve operates like a spool valve to direct the flow of the engine coolant to the bypass, the heat exchanger, or partially to each. Since conventional thermostats are passive devices they lag in response to dynamic engine conditions, and under certain circumstances overheating can occur as a result of the device’s inability to respond quickly. Also, conventional thermostats are designed to protect an engine against overheating year round. Therefore, a thermostat designed to protect against overheating in the summer will often result in an overcooling condition in the winter. One possible solution to the problem is to control the thermostat electrically through the electronic engine control system, or other system, making the thermostat an active control device instead of a passive one. In this study, a mathematical model is developed to determine wax temperature, and thereby predict the thermostat operation and response. The wax temperature depends on the heat transfer from the engine coolant through the brass cup that encapsulates the wax, as well as heat transfer from the heater. The simulations are compared with measurements of temperature, thermostat position and flow at several locations around the thermostat in an experimental set-up. The outcome is used to analyze the accuracy of the methods used in the thermodynamic calculations.

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