Three methods were used to analyze the existence of counter current flow limitation (CCFL) in vertical rectangular narrow channels with varying gap sizes:
1. Comparing the time it took for cooling water to flow through the channel without heating versus with initial heating of the plates to 500°C. Smaller gap sizes resulted in longer times, indicating stronger CCFL effects.
2. Analyzing the vapor and water superficial velocities - CCFL occurs when the vapor velocity is higher than the water velocity. For all gap sizes, the vapor velocity was higher, showing CCFL was present.
3. Examining the rewetting time and critical heat flux (CHF) values. Under the same initial temperature,
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
Evaluation of Convective Heat Transfer Coefficient of Air Flowing Through an ...Bishal Bhandari
The heat transfer coefficient is the most influential parameter in designing of the ducts. The heat transfer coefficient varies with varying velocity, inclination and heat input. The nature of the graph of the convective heat transfer coefficient for a different velocity of air and at a different inclination of the circular Duct was plotted and the result was discussed.
EXPERIMENTAL ANALYSIS OF HEAT TRANSFER AND FLUID FLOW IN MICRO-CHANNEL HEAT SINKijmech
In this paper heat transfer in single phase through micro-channels was studied. The validation of classical correlations of conventional channels to micro-channels is explored. It is found that classical approach is in good agreement with the experimental results of heat transfer in micro-channels .The material used for micro-channel heat sink (MCHS) is copper, experiments were conducted using water as cooling agent in
this study. Micro-channels are made with the help of EDM machine on the upper surface of MCHS. Variation of heat transfer rates, effect of friction factor, effect of pressure drop and variation in temperature distribution is investigated in this study. It is observed in the study that with decrease in
velocity flow friction also decreases.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Performance Analysis of Copper Twisted Tape Inserts for Heat Transfer in A Ci...IJERA Editor
Thermal Performance of heat transfer devices can be improved by heat transfer enhancement techniques. In the present study, heat transfer from hot air to cold water by double pipe heat exchanger for plain tube and plain tube with twisted inserts is experimentally investigated at isothermal condition. The twisted tape inserts when placed in the path of the flow of the fluid, create a high degree of turbulence resulting in an increase in the heat transfer rate. By inserting twisted tape with twist ratio y=5 and y=7 in a concentric tube heat exchanger, the Nusselt number increases gradually from 920 to 6700 and it is 12-15 % higher than plain tube. This is due to the generation of secondary flow in the tube (turbulence flow). Also the heat transfer coefficient is 15 % higher than the plain tube due to increase in degree of swirl.
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
Evaluation of Convective Heat Transfer Coefficient of Air Flowing Through an ...Bishal Bhandari
The heat transfer coefficient is the most influential parameter in designing of the ducts. The heat transfer coefficient varies with varying velocity, inclination and heat input. The nature of the graph of the convective heat transfer coefficient for a different velocity of air and at a different inclination of the circular Duct was plotted and the result was discussed.
EXPERIMENTAL ANALYSIS OF HEAT TRANSFER AND FLUID FLOW IN MICRO-CHANNEL HEAT SINKijmech
In this paper heat transfer in single phase through micro-channels was studied. The validation of classical correlations of conventional channels to micro-channels is explored. It is found that classical approach is in good agreement with the experimental results of heat transfer in micro-channels .The material used for micro-channel heat sink (MCHS) is copper, experiments were conducted using water as cooling agent in
this study. Micro-channels are made with the help of EDM machine on the upper surface of MCHS. Variation of heat transfer rates, effect of friction factor, effect of pressure drop and variation in temperature distribution is investigated in this study. It is observed in the study that with decrease in
velocity flow friction also decreases.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Performance Analysis of Copper Twisted Tape Inserts for Heat Transfer in A Ci...IJERA Editor
Thermal Performance of heat transfer devices can be improved by heat transfer enhancement techniques. In the present study, heat transfer from hot air to cold water by double pipe heat exchanger for plain tube and plain tube with twisted inserts is experimentally investigated at isothermal condition. The twisted tape inserts when placed in the path of the flow of the fluid, create a high degree of turbulence resulting in an increase in the heat transfer rate. By inserting twisted tape with twist ratio y=5 and y=7 in a concentric tube heat exchanger, the Nusselt number increases gradually from 920 to 6700 and it is 12-15 % higher than plain tube. This is due to the generation of secondary flow in the tube (turbulence flow). Also the heat transfer coefficient is 15 % higher than the plain tube due to increase in degree of swirl.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Effect Of Cuo-Distilled Water Based Nanofluids On Heat Transfer Characteristi...IJERA Editor
In this paper, the heat transfer and pressure drop characteristics of the distilled water and the copper oxide-distilled water based nanofluid flowing in a horizontal circular pipe under constant heat flux condition are studied. Copper oxide nanoparticles of 40nm size are dispersed in distilled water using sodium dodecyl sulphate as surfactant and sonicated the nanofluid for three hour. Both surfactant and sonication increases the stability of the nanofluid. The nanofluids are made in three different concentration i.e. 0.1 Vol. %, 0.25 Vol. % and 0.50 Vol. %. The thermal conductivity is measured by KD2 PRO, density with pycnometer, viscosity with Brookfield LVDV-III rheometer. The results show that the thermal conductivity increases with both temperature and concentration. The viscosity and density increases with concentration but decreases with temperature. The specific heat is calculated by model and it decreases with concentration. The experimental local Nusselt number of distilled water is compared with local Nusselt number obtained by the well known shah equation for laminar flow under constant heat flux condition for validation of the experimental set up. The relative error is 4.48 % for the Reynolds number 750.9. The heat transfer coefficient increases with increase in both flow rate and concentration. It increases from 14.33 % to 46.1 % when the concentration is increased from 0.1 Vol. % to 0.5 Vol. % at 20 LPH flow rate. Friction factor decreases with increase in flow rate. It decreases 66.54 % when the flow rate increases from 10 LPH to 30 LPH for 0.1 Vol. %.
NUMERICAL INVESTIGATION OF LAMINAR NANOFLUID FLOW IN MICRO CHANNEL HEAT SINKS IAEME Publication
The effect of using nanofluids on heat transfer and aerodynamics characteristics in rectangular shaped micro channel heat sink (MCHS) is numerically investigated for Reynolds number range of (100-400 ) and different value of heat flux (50 , 100, 150 ) / . In this study,the MCHS performance using tow type of nanofluid with volume
fraction 10% was used as a coolant is examined. The three-dimensional steady, laminar flow and heat transfer governing equations are solved using The computational fluid dynamics code (FLUENT). The MCHS performance is evaluated in terms of temperature profile, heat transfer,velocity profile, pressure drop and friction factor.
An Experimental Research on Heat Transfer Enhancement of a Circular Tube with...IRJESJOURNAL
ABSTRACT:- In the literature, internal tube baffles are widely studied. There is a lack of data for baffles mounted on outside of the tubes. This study aims to fill this gap. Therefore, the effect of baffle inclination angles on heat transfer improvement has been studied experimentally. The experiments were carried out for forced convection of air on a circular tube with inclined baffles. Air has been used as the cold fluid. Experimental results for eight different velocities of air flow (2 – 20 m/s) are presented. Pitch between baffles is 12 mm.The baffle inclination angles with respect to the tube axis were 45º, 60º and 80º. Water temperature is fixed as 65 °C. According to the experimental results, the baffles with an inclination angle of 45º enhance the heat transfer over 60º and 80º around 13.7 % and 10.5 %, respectively. However, pressure drop values for 45º and 60º are 18 % higher than pressure drop values for 80º. The empirical correlations of the Nusselt number have also been obtained for each angle.
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Experimental Investigation of Vertical Downward Flow Boiling Heat Transfer i...IJMER
The present work is carried to determine the two phase heat transfer coefficient during flowing
vertical downward in the minichannel. The minichannel test section is made up of aluminum having
hydraulic diameter 1.33mm. The experiments were carried out by varying mass flow rate from 0.1g/sec to
0.3g/sec of steam at three different vapour qualities of 0.2, 0.4 and 0.6. The result showed as the heat flux
increases there is an increase in two phase heat transfer coefficient upto 20000W/m2 0C. In addition to
that there is a decrease in treand of heat transfer coefficient for vapour quality.
EXPERIMENTAL INVESTIGATION ON BOILING HEAT TRANSFER USING R134AJournal For Research
The heat transfer characteristic of R134a during boiling were experimentally investigated in a horizontal mini channels. The experiments used different parameters like saturation temperature, mass flux, vapour quality, channel diameter, channel geometry and thermo physical properties on the heat transfer coefficients. Several literatures are used to find a assessment correlations and experimental analysis to prepare an experimental setup and their results validation. Boiling heat transfer correlations and theoretical solutions are used to predict the experimental data in this research.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Experimental Study of Heat Transfer Analysis in Vertical Rod Bundle of Sub Ch...IJMER
The ability of the fluid in taking the heat generated by the nuclear reactor fuel is one
important aspect of reactor safety. These capabilities must be kept high enough to maintain integrity of
the fuel cladding as inside retaining radioactive substances. Study characteristics of forced convection in
the fluid water using seven vertical cylinders heated uniformly in the composition ratio of hexagons with
Pitch/Diameter (P/D) at 1.58 in the hexagon-shaped shell model of the reactor core test equipment in
order to obtain the correlation equation displacement convection force. In this study, the heat flux and
velocity of fluid flow greatly affect the temperature of the fluid. The greater the heat flux given the fluid
temperature is getting higher because of the greater heat flux on the cylinder heating the heat absorbed
by the fluid is also getting bigger. Similarly, the velocity of fluid flow, increasing the velocity of the fluid
flow, the smaller the fluid temperature because by increasing the velocity of fluid flow in the sub channel
the heat received by the fluid on the wane led to the smaller fluid temperature. Heat transfer coefficient
results obtained at a velocity flow of 0.1 m s-1
is 500 Wm-2K
-1
to 23 500 Wm-2K
-1
, at a velocity flow of 0.3
m s
-1
is 3 100 Wm-2K
-1
up to 2 800 Wm-2K
-1
and in velocity flow of 0.5 m s-1
is 3 500 Wm-2K
-1
to 32 500
Wm-2K
-1
. In this experimental study use forced convection flow has a Reynolds number range from 3 991
to 29 537 and Graetz numbers from 1 371 to 41 244. The correlation of forced convection heat transfer as
follows: Nu forced = 1.641 Gz 0.4267
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Effect Of Cuo-Distilled Water Based Nanofluids On Heat Transfer Characteristi...IJERA Editor
In this paper, the heat transfer and pressure drop characteristics of the distilled water and the copper oxide-distilled water based nanofluid flowing in a horizontal circular pipe under constant heat flux condition are studied. Copper oxide nanoparticles of 40nm size are dispersed in distilled water using sodium dodecyl sulphate as surfactant and sonicated the nanofluid for three hour. Both surfactant and sonication increases the stability of the nanofluid. The nanofluids are made in three different concentration i.e. 0.1 Vol. %, 0.25 Vol. % and 0.50 Vol. %. The thermal conductivity is measured by KD2 PRO, density with pycnometer, viscosity with Brookfield LVDV-III rheometer. The results show that the thermal conductivity increases with both temperature and concentration. The viscosity and density increases with concentration but decreases with temperature. The specific heat is calculated by model and it decreases with concentration. The experimental local Nusselt number of distilled water is compared with local Nusselt number obtained by the well known shah equation for laminar flow under constant heat flux condition for validation of the experimental set up. The relative error is 4.48 % for the Reynolds number 750.9. The heat transfer coefficient increases with increase in both flow rate and concentration. It increases from 14.33 % to 46.1 % when the concentration is increased from 0.1 Vol. % to 0.5 Vol. % at 20 LPH flow rate. Friction factor decreases with increase in flow rate. It decreases 66.54 % when the flow rate increases from 10 LPH to 30 LPH for 0.1 Vol. %.
NUMERICAL INVESTIGATION OF LAMINAR NANOFLUID FLOW IN MICRO CHANNEL HEAT SINKS IAEME Publication
The effect of using nanofluids on heat transfer and aerodynamics characteristics in rectangular shaped micro channel heat sink (MCHS) is numerically investigated for Reynolds number range of (100-400 ) and different value of heat flux (50 , 100, 150 ) / . In this study,the MCHS performance using tow type of nanofluid with volume
fraction 10% was used as a coolant is examined. The three-dimensional steady, laminar flow and heat transfer governing equations are solved using The computational fluid dynamics code (FLUENT). The MCHS performance is evaluated in terms of temperature profile, heat transfer,velocity profile, pressure drop and friction factor.
An Experimental Research on Heat Transfer Enhancement of a Circular Tube with...IRJESJOURNAL
ABSTRACT:- In the literature, internal tube baffles are widely studied. There is a lack of data for baffles mounted on outside of the tubes. This study aims to fill this gap. Therefore, the effect of baffle inclination angles on heat transfer improvement has been studied experimentally. The experiments were carried out for forced convection of air on a circular tube with inclined baffles. Air has been used as the cold fluid. Experimental results for eight different velocities of air flow (2 – 20 m/s) are presented. Pitch between baffles is 12 mm.The baffle inclination angles with respect to the tube axis were 45º, 60º and 80º. Water temperature is fixed as 65 °C. According to the experimental results, the baffles with an inclination angle of 45º enhance the heat transfer over 60º and 80º around 13.7 % and 10.5 %, respectively. However, pressure drop values for 45º and 60º are 18 % higher than pressure drop values for 80º. The empirical correlations of the Nusselt number have also been obtained for each angle.
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Experimental Investigation of Vertical Downward Flow Boiling Heat Transfer i...IJMER
The present work is carried to determine the two phase heat transfer coefficient during flowing
vertical downward in the minichannel. The minichannel test section is made up of aluminum having
hydraulic diameter 1.33mm. The experiments were carried out by varying mass flow rate from 0.1g/sec to
0.3g/sec of steam at three different vapour qualities of 0.2, 0.4 and 0.6. The result showed as the heat flux
increases there is an increase in two phase heat transfer coefficient upto 20000W/m2 0C. In addition to
that there is a decrease in treand of heat transfer coefficient for vapour quality.
EXPERIMENTAL INVESTIGATION ON BOILING HEAT TRANSFER USING R134AJournal For Research
The heat transfer characteristic of R134a during boiling were experimentally investigated in a horizontal mini channels. The experiments used different parameters like saturation temperature, mass flux, vapour quality, channel diameter, channel geometry and thermo physical properties on the heat transfer coefficients. Several literatures are used to find a assessment correlations and experimental analysis to prepare an experimental setup and their results validation. Boiling heat transfer correlations and theoretical solutions are used to predict the experimental data in this research.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Experimental Study of Heat Transfer Analysis in Vertical Rod Bundle of Sub Ch...IJMER
The ability of the fluid in taking the heat generated by the nuclear reactor fuel is one
important aspect of reactor safety. These capabilities must be kept high enough to maintain integrity of
the fuel cladding as inside retaining radioactive substances. Study characteristics of forced convection in
the fluid water using seven vertical cylinders heated uniformly in the composition ratio of hexagons with
Pitch/Diameter (P/D) at 1.58 in the hexagon-shaped shell model of the reactor core test equipment in
order to obtain the correlation equation displacement convection force. In this study, the heat flux and
velocity of fluid flow greatly affect the temperature of the fluid. The greater the heat flux given the fluid
temperature is getting higher because of the greater heat flux on the cylinder heating the heat absorbed
by the fluid is also getting bigger. Similarly, the velocity of fluid flow, increasing the velocity of the fluid
flow, the smaller the fluid temperature because by increasing the velocity of fluid flow in the sub channel
the heat received by the fluid on the wane led to the smaller fluid temperature. Heat transfer coefficient
results obtained at a velocity flow of 0.1 m s-1
is 500 Wm-2K
-1
to 23 500 Wm-2K
-1
, at a velocity flow of 0.3
m s
-1
is 3 100 Wm-2K
-1
up to 2 800 Wm-2K
-1
and in velocity flow of 0.5 m s-1
is 3 500 Wm-2K
-1
to 32 500
Wm-2K
-1
. In this experimental study use forced convection flow has a Reynolds number range from 3 991
to 29 537 and Graetz numbers from 1 371 to 41 244. The correlation of forced convection heat transfer as
follows: Nu forced = 1.641 Gz 0.4267
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
Aim:
To determine the heat loss in a double pipe heat exchanger counter-current flow
experiment.
Theory:
A double-pipe heat transfer exchanger consists of one or more pipes placed
concentrically inside another pipe of a larger diameter with appropriate fittings to direct
the flow from one section to the next. One fluid flows through the inner pipe (tube side)
in this experiment (hot water), and the other flows through the annular space (annulus)
(cold water).
The double-pipe heat exchanger is one of the basic kinds of exchangers with a very
flexible configuration. There are two types of counterflow or parallel flow for this type
that are the basis of design and calculation for determining pipe size, length, and
number of bends.
Double pipe heat exchanger counter current: heat is exchanged between two flowing
fluids at a different temperature that flows counter current in the heat exchanger double
pipe.
The efficiency is greater in counter-current than in parallel flow because the two fluids
(water) flow separately in counter-current flow when the high different temperatures
meet heat exchange rapidly due to the difference of temperatures, the hot water
becomes warm then cold as heat exchanges, and the cold water becomes warm the heat
exchange occurs till it reaches steady state. As it is explained in Figure 1.
Heat loss can be found by the equation below:
Q=ΔH=mCpΔT
Where: Q=ΔH is the amount of heat transferred to or from the system (J).
m: mass of the system (Kg)
Cp: constant pressure specific heat capacity of the system (J/g°C)
ΔT: difference in temperature of the system °C.
Experiment: Double pipe heat exchanger
4
Figure 1: concurrent and countercurrent respectively.
Procedure:
Double pipe heat exchanger: as shown in the figure-2:
1. Power switch: No.1
2. Temperature scale to select a temperature to heat the water in the tank [No.2] in
the figure.
3. Water tank a heating coil is used to heat the water [no.3].
4. Power pump to set a flow rate, the water is pumped through the double pipe heat
exchanger. [No.4]
5. A flow rate measurement is found in no.5
6. [No.6-7-8-9-10] The temperature measurements measure temperature
throughout the process.
7. Then the temperature and flow rate are collected in the temperature screen.
Experiment: Double pipe heat exchanger
5
Figure 2: double pipe heat exchanger.
Experiment: Double pipe heat exchanger
6
observation:
1. Turn on the device with the power switch.
2. The flow rate is set as 157 ml/s.
3. Heat water up to [40-50 Celsius] in this experiment: [44.4 Celsius] by the
heating coil in the water tank, set the desired temperature by the temperature
scale in the water tank.
4. Then water is pumped to the pipes by the power pump.
5. Adjust the valves so that the hot water and cold water flow countercurrent.
6. The hot water flows in the inner pipe in the double pipe through the pipe from
the pump to the heat exchanger
7. the cold water flows in the outer pipe counter current from the tank to the pipes
the valv
AN EXPERIMENTAL STUDY OF EXERGY IN A CORRUGATED PLATE HEAT EXCHANGERIAEME Publication
In the present work an attempt has been made to investigate the performance of a 3 channel 1-1 pass, corrugated plate heat exchanger. The plates had sinusoidal wavy surfaces with corrugation angle of 450. Hot water at different inlet temperature ranging from 400C to 600C was made to flow in the central channel to get cooled by water in the outer channels.
HEAT TRANSFER AUGMENTATION IN STEEL QUENCHING BY SPRAY IMPINGEMENT COOLING ME...BIBHUTI BHUSAN SAMANTARAY
The present article discusses the experimental results on heat transfer characteristics of spray impingement cooling of a stationary steel plate. The eexperimental setup consisted of an electrically heated flat stationary steel plate of dimension 120 mm x 120 mm x 4 mm, spray setup, water supply and air supply unit. The effects of various controlling parameters such as air-water pressures, water flow rate, nozzle tip to target distance and impingement density were determined and analysed. The cooling rates were computed from the time dependent temperature history and used to analyse the parametric effects. The results obtained in the study confirmed the higher efficiency of the spray cooling system and the cooling strategy was found advantageous over the conventional cooling methods available in the open literature.
SUMMARYThis report represents the outcome of heat exchang.docxpicklesvalery
SUMMARY:
This report represents the outcome of heat exchange via 4 tubes that are fitted within the shell with four thermocouples to determine the temperature for every pass, two passes for the hot water (in/out) and two for the cold water (in/out). The experiment was commencing according to the amount of hot and cold water that was supplied to the inputs of the heat exchange. The supply was managed by the use of taps that would restrain or allow the gush of water. The temperature for the inputs was constant in the most of the 5 runs while the outputs had been changed due to heat exchange occurring within the shell. Hot water had lost temperature while cold water had gained temperature.
An experiment was set up to resolve the energy losses that affect the hot and cold water, by using thermodynamic laws. During the experiment the water gush rates were measured carefully and the data had been collected and entered to allow the calculations of the energy losses that came out. Finally, it was discovered the heat had been exchanged from the hot into the cold to maintain the temperature inside the shell.
Contents:
SUMMARY:i
1.0INTRODUCTION:1
2.0AIM:1
3.0EXPERIMENTAL METHOD:1
4.0EXPERIMENTAL DATA:2
5.0DATA ANALYSIS:2
6.0DISCUSSION:4
7.0CONCLUSION4
ii
INTRODUCTION:
The exchanger consists of a number of tubes that sit inside a shell that allows cold water to flow through them. Hot water flow through the bordering shell and the two fluids exchange heat. Heat exchanger can come in various forms and as such can have many different motives. A radiator in a car and a boiler in a steam engine are both heat exchanger with the radiator cooling the engine, and the boiler exchanging raw materials into steam that can be used for power generation. The heat exchanger that has been used in this experiment was a basic shell and tube style as shown in figure 1. A Jenco digital thermometer and Jenco thermocouple switches are used in the heat exchanger set up to allow to calculate the measurements for the experiment. Flow meters fitted on the inlet of hot and cold water taps are used to change volume flow rates.
AIM:
The aim of the report is to evaluate the heat losses that came out for the hot water. The experiment will carry of recording temperatures and flow rates and then calculating other possible factors that may cause heat loss.EXPERIMENTAL METHOD:
1) Be familiar with the different part of the experimental.
2) Turn on the cold and hot water taps.
3) Turn valves for the cold water at an initial flow rate (approximate 15 L/min for cold water) Make sure that all the water passes through the flow meters (turn off one of the valves in each water supply line)
4) Water for couple of minutes before reading the data.
5) Take the temperature reading for the thermocouples 1 to 5 by press the Jenco thermocouple buttons.
6) Repeat steps from 3) to 5) for 5 different flow rate combinations.EXPERIMENTAL DATA:
Room temperature: 15°C
Run/Quantities
(L/min)
(L/min)
in ...
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Research Inventy : International Journal of Engineering and Scienceinventy
Research Inventy : International Journal of Engineering and Science
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed
Basic Study on Solid-Liquid Phase Change Problem of Ice around Heat Transfer ...IJERDJOURNAL
Abstract:- Phase change heat transfer around heat transfer tubes is one of the basic problem of an ice heat storage exchanger. It can lead to decrease of thermal storage efficiency and damage of heat transfer tubes if continued freezing further after the ice has bridged because of the generated ice thermal resistance and volume expansion. In this study, we focused on freezing phenomena of phase change material (PCM) between two heat transfer tubes, which can simulate an inside structure of ice heat storage exchangers. Bridging time between two heat transfer tubes was studied numerically. We used water as the PCM, which is filled in the water container. Two horizontal elliptical tubes were used as heat transfer tubes in order to observe the influence of natural convection. Single-domain calculation model was used to calculate arbitrary shape of the two tubes during the ice freezing process. We changed arranged angle and relative position of the tubes to investigate impact of the tube arrangement on freezing phenomenon. In order to confirm the accuracy of our analysis, analytical results were compared with experimental results at the same conditions. Results show that the bridging time was not simply in proportional to the initial temperature of water when considered the natural convection influenced by such as density inversion of water. Moreover, we found that when we set the temperature of tube wall and initial temperature of water as the parameters, bridging time has a similar trend with distance between the axes. Therefore, it is possible to predict the bridging time for elliptical heat transfer tube.
Effect of controlling parameters on heat transfer during spray impingement co...BIBHUTI BHUSAN SAMANTARAY
The heat transfer characteristics of air-water spray impingement cooling of stationary steel plate was experimentally investigated. Experiments were conducted on an electrically heated flat stationary steel plate of dimension 120 mm x 120 mm x 4 mm. The controlling parameters taken during the experiments were air-water pressures, water flow rate, nozzle tip to target distance and mass impingement density. The effects of the controlling parameters on the cooling rates were critically examined during spray impingement cooling. Air assisted DM water was used as the quenchant media in the work. The cooling rates were calculated from the time dependent temperature profiles were recorded by NI-cRIO DAS at the desired locations of the bottom surface of the plate embedded with K-type thermocouples. By using MS-EXCEL the effects of these cooling rate parameters were analysed The results obtained in the study confirmed the higher efficiency of the spray cooling system and the cooling strategy was found advantageous over the conventional cooling methods in the present steel industries.
Esign and thermal evaluation of shell and helical coil heat exchangereSAT Journals
Abstract
Heat exchangers are the important engineering equipments used for transferring heat from one fluid to another. Heat exchangers are widely used in various kinds of application such as power plants, nuclear reactors, refrigeration and air-conditioning systems, heat recovery systems, petrochemical, mechanical, biomedical industries. Helical coil heat exchangers are gaining wide importance now-a-days because it can give high heat transfer coefficient in small footprint of surface area. This paper focuses on the designing of shell and helical coil heat exchanger and its thermal evaluation with counter flow configuration. The thermal analysis is carried out considering the various parameters such as flow rate of cold water, flow rate of hot water, temperature, effectiveness and overall heat transfer coefficient.
Keywords— Helical coil heat exchanger, Counter flow, Flow rate, effectiveness, heat transfer coefficient etc.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
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Analysis of effect gapsize to counter current flow limitation knep bali 2014
1. Some Methods to Know Effect of Gap Size on Counter Current Flow Limitation
in Vertical Rectangular Narrow Channel
IGN. Bagus Catrawedarma
1
, Indarto
2
, Mulya Juarsa
3
1
Faculty of Engineering, Indonesia Hindu University, Bali, Indonesia
2
Mechanical and Industrial Engineering Department, Faculty of Engineering, Gadjah Mada University, Indonesia
3
Indonesia National Nuclear Energy Agency, Tangerang, Indonesia
Email: ngurahcatra@yahoo.com
Abstract
Effect of gap size on counter current flow limitation (CCFL) in vertical rectangular channel was studied from
experimental result. It was be conducted by using two vertical plates with 1 mm, 2 mm, and 3 mm narrow gap.
Initial temperature of the plate is about 500o
C. Debit and temperature of cooling water were controlled about
0,09 l/s and saturated temperature. As the result showed that some methods can be used to know the existence
of CCFL in the vertical rectangular narrow channels. The methods that used in this work are by comparing of
vapor contraction time between without heating and with heating, by comparing the vapor and the water
superficial velocity, by rewetting time, and by comparing CHF this experiment to other correlation. For all of the
methods are concluded that the smaller gap size, the stronger CCFL effect.
Keywords: narrow gap, gap size, superficial velocity, rewetting time, CHF, CCFL
Nomenclature
Symbol Means Dimension
ℎ
∗
∗
A
c
Dh
dT/dt
m
Nu
q
Tinitial
TC
w
ΔTexcess
Flow area
Bond number
Wallis constant
Specific heat of plate
Plate thickness
Hydraulic diameter
Transient temperature
Leinhard constant
Gravitational acceleration
Heat of evaporation
Vapor superficial velocity
Liquid superficial velocity
Non dimensional superficial velocity of vapor
Non dimensional superficial velocity of liquid
Thermal conductivity of vapor
Characteristic length
Heated length
Wallis constant
Nusselt number
Water flow rate
Heat Flux
Critical Heat Flux
Initial plate temperature
Thermocouple
Width of plate
Excess temperature
Gap size
m
2
-
-
J/kg.
o
C
mm
mm
o
C/s
-
m/s
2
W/m
2
.
o
C
m/s
m/s
-
-
W/m.
o
C
m
m
-
-
L/s
W/m
2
W/m
2
o
C
-
m
o
C
mm
2. 1. INTRODUCTION
Three mile island 2 (TMI-2) nuclear accident is one of the case of CCFL effect in narrow channel. It is
formed between debris and wall reactor pressure vessel (RPV). Based on Juarsa [2] opinion that the debris has
been cooled by water in the bottom reactor and it can’t exit from RPV wall, so reactor condition can be controlled.
When the debris move to bottom, then a part of cooling water volume is moving to upper part and evaporation
Plate density
Vapor density
Liquid density
Surface tension
kg/m
3
kg/m
3
kg/m
3
N/m
3. process is occurred. The vapor is moving to upper part but the cooling water is continually flowing to the bottom,
then it is occurred counter current flow between vapor and cooling water (see Figure 1). So, effect of CCFL in
narrow channel is very important to be considered during cooling process in nuclear reactor.
Figure 1. Narrow gap in the nuclear reactor [5]
Many experiments about CCFL in narrow channel have been conducted by researchers. Sudo and
Kaminaga [6] was investigating characteristic of CHF based on CCFL correlation and experimental CHF. It was
conducted by water as fluid test. The sizes of channel are 750 mm of length, 50 mm of width, 2.25 mm of gap
and 375 mm of length, 50 mm of width, 2.80 mm of gap. The experimental results are indicating that aspect ratio
has important role to CCFL and CHF characteristics. It was strongly implied that the CHF for downward flow is at
a minimum under the flooding condition in the case of large inlet water sub cooling and when the inlet downward
water mass flux is greater than that under the flooding condition in the case of small inlet water sub cooling.
Murase et.al [4] was analyzing heat transfer in narrow channel based on data from other researchers. It shows
that heat flux in narrow channel is larger than pool nucleat boiling in low superheat condition. It is caused by
restricted flow area and it reached CHF by CCFL. Zhang et al [8] was studying boiling curve in vertical annulus
narrow channel heated from one side. The initial temperatures were variated from 500°C to 800°C and the gap
sizes were changed from 0.5 mm to 7.0 mm. The results indicated that the heat transfer during cooling in the
channel was significantly limited by the CCFL. Under the same initial temperature, if the smaller gap size, the
longer rewetting time and the lower CHF. It is caused by existence of CCFL in the channel. Juarsa and
Antariksawan [2] were investigating heat transfer in vertical annulus narrow gap heated from one side. The initial
temperature is 800°C. 1.0 mm and 4.0 mm gap sizes are used. The results indicated that boiling in the 1.0 mm
gap size is so influenced by CCFL.
The previous experiments are indicating that the experiments about cooling process in the narrow gap are
one of the complex analisis because it is influenced by some variables. Therefore, this study is focusing effect of
gap size to CCFL in vertical rectangular narrow channel heated from both sides. Existence of CCFL is analyzed
by comparing the time of flowing water in the channel from starting process until it exit from the channel, by
rewetting time, by superficial velocity, and by value of CHF. The time of flowing water is compared between
testing time without heating and with heating.
2. THEORETICAL
2.1 Superficial velocity
Existence of CCFL based on superficial velocity is calculated by Wallis [7], that is:
∗ /
+ ∗ /
= (1)
where:
∗
=
. . ( − )
/
(2)
∗
=
. . ( − )
/
(3)
and:
= (4)
L= heated length of channel (m)
t = average time of water to flow through the rectangular channel during the heated condition.
The constant c and m are calculated by:
= 0.66
/
(5)
= 0.5 + 0.0015 . (6)
4. Where:
=
. . . ( − )
(7)
2.2 Heat flux correlation
Heat flux is rate of heat transfer per area. The correlation used in this work is:
= . . . (8)
and are obtained from properties of stainless steel.
2.3 Other correlations at each boiling regime
a. Bromley [1] correlation is used in film boiling regime. It was be got from pool boiling experiment. It is:
=
. . − ∆ℎ
.
,
× ∆ ,
(9)
C = 0,667 – 0,943
< 2
−
,
→ =
> 2
−
,
→ = 2
−
,
b. Laminer vapor correlation is also used in film boiling regime. It is:
= . ∆ (10)
Where Nu is relating to bilateral heated and geometry plate.
c. Leinhard [3] correlation is used to know value of CHF for pool boiling case:
= 0,149 . ℎ .
/
. . −
/
(11)
3. EXPERIMENTAL APPARATUS AND PROCEDURE
This experiment is a joint two facilities. They are Untai Uji Beta (UUB) and HeaTiNG-02 (see Figure 2).
UUB is used to set-up flow rate and temperature of cooling water before it is flowed to the channel. UUB has a
centrifugal pump for setting-up flow rate of the cooling water and circulating it, flow meter is used to know mass
flow rate of the cooling water, pre heater is used to increase the cooling water temperature, thermocouple is
used to measure the temperature, and some of valves is used to open or close the cooling water flow. HeaTiNG-
02 is the main test section. It has main and cover stainless steel plates with 8 mm and 3 mm thickness, 1100 mm
length, 50 mm width. Narrow gaps of the main and cover plates are changed from 1.0 mm, 2.0 mm and 3.0 mm.
The main and cover plates have three chromel-alumel thermocouples (Figure 3). It is used to measure of
temperature during heating and cooling process. Figure 2 show the schematic apparatus.
5. Figure 2. (A) Schematic apparatus, (B) Detail HeaTiNG-02
Figure 3. Thermocouple position on main and cover plate
WinDAQ T1000 Acquisition data is used to measure plate temperature during process with 1 data per
second. Slide regulator with the 25 kW maximum power is used to change power input during heating process
until the plate temperature is about 500°C. The power input was gradually increased in order to uniform
temperature.
The experiment is started by setting up the gap size with the range is showed in Table 1, then the plates
are heated by ceramic heater until the initial temperature is about 500°C. If it has been reached, the ceramic
1
2
3
5
6
4
1 : Channel
2 : Main plate
3 : Position of thermocouple
4 : Cover plate
5 : SS-316 window
6 : Heater
7 : Insulating Ceramic Brick
7
( A )
( B )
Tank
Condensor
To ECWS
From ECWS
PumpFlow meter
HeaTiNG-02
Preheater
T P
Untai Uji Beta
6. heater is switched off, then 0.09 L/s and about 90°C of cooling water that controlled at UUB is flowed to the
channel. If all of the temperatures are closing to 90°C, the experiment is stopped.
Table 1. Experimental variable
4. RESULTS AND DISCUSSIONS
4.1 Time Testing
Comparison of time testing without heating and with heating can be used as a indicator of existence of
CCFL in narrow channel (see Table 2). Time testing without heating is calculated when the plates are not heated.
It is started from cooling water flowed to the channel until it is exit from that. Time testing with heating is
calculated when the plates are heated until initial temperature is about 500°C.
Based on the comparisons of time testing without heating and with heating are known that for all of the
gap size have been existed CCFL in the channel. It is also analyzed that the longer the gap size, the faster the
cooling water exit from the channel. It is indicating that the smaller the gap size, the longer time of vapor
contraction in the channel, so the longer the time is needed by water to contact the surface plate, therefor the
stronger effect of CCFL in the channel. CCFL is the phenomena counter current flow between water and vapor
in vertical channel.
Table 2. Time testing
4.2 Superficial Velocity
Figure 4 is representing of vapor and water non dimensional superficial velocity. It is calculated by
equation (1) to (7) before it is plotted on a graph. The CCFL is occurred in the channel, if superficial velocity of
vapor is higher than the superficial velocity of water. It can be showed from Figure 4 that all of the gap size is
affected by CCFL and the 1 mm gap size has the strongest CCFL effect. It is caused by value of Jg
*
is higher
than Jl
*
. Figure 4 is also known that the larger the gap size, the smaller the CCFL effect.
Figure 4. Non dimensional superficial velocity
4.3 Transient temperature
0,020 0,025 0,030 0,035 0,040
1,4
1,5
1,6
1,7
1,8
1,9
2,0
mm
mm
mm
(j
*
g)
1/2
+ 33,48 (j
*
l )
1/2
= 2,71
(j
*
l )
1/2
(j
*
g)
1/2
Variable
Value
I II III
Gap size (mm) 1.0 2.0 3.0
Initial temperature (
o
C) 500 500 500
Cooling water mass flow rate (L/s) 0.09 0.09 0.09
Cooling water temperature (
o
C) 90.0 90.0 90.0
Tinitial
(
o
C)
Gap size ()
(mm)
Time testing
without heating
(minute)
Time testing with heating
Time of starting vapor
contraction
(minute)
Time of finishing
vapor contraction
(minute)
500
1,0 2,84 0 8,75
2,0 1,25 0 3,41
3,0 0,80 1,65 3,42
7. Rewetting point can be kown from transient temperature. Rewetting point is a condition when the cooling
water contact to the surface plate. It is indicated by drastically drop temperature. Figure 5 is showing that the
smaller the gap size, the longer the rewetting time. It is caused by the smaller mass flow rate of water cooling, the
longer the time of vapor contraction in the channel, so the longer the contact time of cooling water to plate
surface. Therefor, the smaller the gap size, the stronger effect of CCFL in the channel.
Figure 5. Transient temperature main plate on TC-6
4.4 Heat Flux
Boiling curve is a representation of heat flux versus ∆Texcess (see Figure 6). Heat flux is calculated from
equation (8) by the transient temperature. It is experimental result. Generally, in the film boiling regime show
that the larger the gap size, the higher the value of heat flux. Film boiling is occurred in the first process. It
keeps to continue until the cooling water contact to the surface of plate. The longer time the film boiling, the
longer the CCFL effect. It is caused by vapor blanket on the plate surface and it is flowing to the upper part
of the channel. So, more inconvenient the water to contact on the surface plate. The smaller the gap size,
the longer the boiling regime, and the stronger the effect of CCFL. It is also known from comparison of film
boiling regime this experiment to Bromley [1] correlation. The larger the gap size, the closer to the Bromley
[1] correlation. It is indicating that the longer the gap size, the closer to the pool boiling. It is caused by the
Bromley [1] experiment was conducted on pool boiling condition. So, the larger the gap size, the lower effect
of CCFL. In other hand, effect of CCFL can also be known from CHF value. The larger the gap size, the
higher the CHF value and the closer to Leinhard [3] correlation. It is indicating that the larger the gap size,
the closer to pool boiling condition because Leinhard [3] conducted the experiment in pool boiling case. It is
characterized by unflowing fluid. So, the larger the gap size, the lower the CCFL effect.
Figure 6. Boiling curve of main plate on TC-6
5. CONCLUSIONS
0 100 200 300 400 500 600 700
0
100
200
300
400
500
Rewetting point
Rewetting point
TC-6, Tinitial
= 500
o
C
= 1 mm
= 2 mm
= 3 mmTemperature(
o
C)
Time (second)
Rewetting point
100
10
1
10
2
10
3
= 1 mm
= 2 mm
= 3 mm
Bromley
Laminer
Leinhard
TC-6 ; Tinitial
= 500
o
C
q(kW/m
2
)
excess
(
o
C)
Film Boiling regime
8. Some methods can be used to know the existence of CCFL in the rectangular narrow channels. The
methods used in this work are by comparing of time vapor contraction between without heating and with heating,
by comparing the vapor and water superficial velocities, by rewetting time, and by comparing CHF this
experiment to other correlations. So, for the all of method is concluded that the smaller gap size, the stronger
CCFL effect.
ACKNOWLEDGEMENT
Thank you very much to Mr. Ismu Handoyo and Mr. Kiswanta for help and carrying attitude. Thanks to
Ministry of Research and Technology, Indonesia Government for Incentive Research Grant 2009. Thanks to
thermal hydraulic research group, Center of Reactor Technology and Safety Nuclear, Indonesia National Nuclear
Energy Agency, Tangerang, Indonesia for their support activity.
REFERENCES
1. Bromley, L.A., Heat Transfer in Stable Film Boiling, Chemical Engineering Program (1950), Vol.46,
pp.221.
2. Juarsa, M., dan Antariksawan, A.R., Effect of Counter Current Flow Limitation on Boiling Heat Transfer
in A Narrow Gap, Tri Dasa Mega Journal of Nuclear Reactor Technology (2007), Vol. 10 No. 1.
3. Lienhard, J.H., , A Heat Transfer Textbook, Third edition, Phlogiston press (2001).
4. Murase, M., Kohriyama, T., Kawabe, Y., Yoshida, Y and Okano, Y., Heat Transfer Models in Narrow
Gap, Proceedings of ICONE 9, Nice (France) (2001), 8 – 12 April.
5. Riyono B, Indarto, Sinta T.H, Mulya Juarsa Analisis Eksperimental Fluks Kalor pada Celah Sempit
Anulus Berdasarkan Variasi Temperatur Air Pendingin Menggunakan Bagian Uji HeaTiNG-01,
Publication text, Gadjah Mada University, 2010
6. Sudo, Y., and Kaminaga, M., A CHF Characteristic for Downward flow in A Narrow Vertical Rectangular
Channel Heated From Both Sides, International Journal Multiphase Flow, (1989) Vol. 15, No. 5, pp. 755-
766.
7. Wallis, G. B., One-dimensional Two-phase Flow, McGraw-Hill, United States of America (1969).
8. Zhang, J., Tanaka, F., Juarsa, M., Mishima, K., Calculation of Boiling Cuves during Rewetting of a Hot
Vertical Narrow Channel, The 10
th
International Topical Meeting on Nuclear Reactor Thermal Hydraulics
(2003).