Name: measuring heat transfer in a tube exchanger
Uploaded: 2023-04-30T06:58:24.000Z
Duration: 11 min 38 s
Channel: JoVE

K12 Standards

Tennessee Academic Standards

High School

Chemistry

Energy

CHEM1.PS3.2

Heat Exchanger Analysis

1. Fabrication of heat exchanger system (see schematic and photograph, Fig. 2)
<ol>
	<li>Affix two plastic water reservoirs (~1 liter each) to a work surface (~0.6 m apart). If these are covered containers, drill holes in the lid for the inlet and outlet water lines and pump power cable. These will serve as the hot and cold water reservoirs.</li>
	<li>Mount one small submersible pump in each reservoir.</li>
	<li>Vertically mount two water flow meters (rotameters), one near each reservoir. Use soft PVC tubing to connect the flow meter inlets to the pump discharge ports.</li>
	<li>Install the heat exchanger (HX) outer tube (~0.3 m long, outer diameter OD = 12.7 mm, inner diameter ID = 9.5 mm) into two compression pipe tee fittings (see Fig. 2). Connect a flexible PVC tube (OD = 12.7 mm, ID = 6.2 mm) from the side port on one tee fitting to the hot flow meter outlet.</li>
	<li>Cut an aluminium tube (OD = 7.9 mm, ID = 6.2 mm) to the length of the heat exchanger, including the tee fittings on the end (~0.38 m long), and insert it into the heat exchanger assembly. The aluminium tube should slide snugly into the soft connecting PVC tube (OD = 12.7 mm, ID = 6.2 mm) at the end of the compression fitting.</li>
	<li>Connect a soft PVC tube from the compression fitting at the other end of the HX assembly to the hot water reservoir. Tighten the compression fittings to seal the soft plastic tubing around the aluminium tube. This will separate the hot flow through the inner aluminium tube from the outer cold flow.</li>
	<li>Connect a flexible PVC tube from the side port on one tee fitting to the cold flow meter outlet. Connect a PVC tube from the side port on the other tee fitting to the cold water reservoir (return flow). The hot and cold stream inlets to the HX should be on opposite ends.</li>
	<li>Drill small holes (~1.6 mm diameter) through one side of the soft plastic tubes near each heat exchanger inlet and outlet port (4 total). Gently insert a thermocouple probe into each port so that the probe tip is approximately in the center of the tube. Connect the thermocouple probes to a thermocouple reader</li>
	<li>Using epoxy or similar adhesive to seal the small gap in the tubes around the thermocouple probes so that no water leaks out.</li>
</ol>
<img alt="Heat exchange process diagram and experimental setup for thermodynamics study; includes flow meters." src="/files/ftp_upload/10391/10391fig2v2.jpg" data-altupdatedat="1761830439000" data-alt="Figure 2"> 
Figure 2: (a) Schematic and (b) labelled photograph of heat exchanger rating experimental system

2. Operation
<ol>
	<li>Fill the cold reservoir with room temperature tap water, and the hot reservoir with warm water.</li>
	<li>Turn on the two water pumps, and use the flow meter needle valves to adjust the flow rates to desired values (e.g., 0.1 l min-1). It may be necessary to circulate water at a higher flow rate initially to clear out trapped air bubbles.</li>
	<li>Allow the system to stabilize for a couple minutes, and then record the four thermocouple measurements representing the inlet and outlet temperatures. Record a few sets of readings for each flow condition. If available, the hold function on the thermocouple reader can freeze readings to help recording.</li>
	<li>Collect temperature measurements at a few sets of hot and cold water flow rates. Periodically refill the reservoirs with fresh hot and cold water to maintain sufficient average temperature differences (~5 - 10°C).</li>
</ol>
3. Analysis
<ol>
	<li>For each condition, compare the hot- and cold-stream energy change rates (<img alt="Heat transfer equation: ṁHcpH(TH,in−TH,out); thermal energy balance; formula." src="/files/ftp_upload/10391/10391eq11.jpg" data-altupdatedat="1761830439000" data-alt="Equation 11">, <img alt="Heat transfer equation, ṁCpC(TC,out−TC,in), thermal energy balance, formula." src="/files/ftp_upload/10391/10391eq12.jpg" data-altupdatedat="1761830439000" data-alt="Equation 12">). For water, cp = 4.2 kJ kg-1 K-1. and the volume flow rate can be multiplied by density (ρwater = 997 kg m-3) to find the mass flow rate. Do the energy change rates (Q) match, as assumed in Eqn. 1?</li>
	<li>Evaluate the LMTD for each condition following Eqn. 2 using Q from Step 3.1. Evaluate the heat exchanger UA (defined in Eqn. 3). Is this quantity approximately constant for considered conditions?</li>
	<li>Evaluate the theoretical UA for fully developed laminar flow in this HX (Eqn. 4) using the mean heat transfer rate ((QC+QH)/2). How does this theoretical value compare to the measured value?</li>
</ol>
<table border="1" cellspacing="0" cellpadding="0" width="518">
	<tr>
		<td width="99" valign="top">Chapter title</td>
		<td width="419" valign="top">Transcript</td>
	</tr>
	<tr>
		<td width="99" valign="top">1</td>
		<td width="419" valign="top">Heat exchangers are ubiquitous components in energy systems. Some common examples are car radiators and refrigerator evaporators. In both cases, the heat exchanger is facilitating the transfer of heat, from one stream of fluid to another. From these examples, it is clear that heat exchangers are important in a variety of systems; Primarily providing thermal management or transitions in thermodynamic cycles. An understanding of how to model and rate heat exchangers is important for optimizing designs and integrating heat exchangers into larger systems. This video will illustrate some principles of heat exchanger design and analysis, and then demonstrate those concepts on a simple tube-in-tube heat exchanger design. At the end, some common applications will be explored.</td>
	</tr>
	<tr>
		<td width="99" valign="top">2</td>
		<td width="419" valign="top">A well designed heat exchanger should facilitate efficient, continuous heat transfer between two fluid streams, without allowing them to mix. As two fluid streams enter a heat exchanger, they are brought into close thermal contact across a physical barrier. Heat exchange is driven by a local temperature differences as the fluids progress, until the fluids reach the exit. The result is that the hotter of the two fluids entering the heat exchanger will exit with a reduced temperature, and the colder of the two with an increased temperature. During steady operation, the heat transfer rate of the hot fluid is determined by the mass flow rate and specific heat of the fluid, multiplied by the difference in temperature between the entrance and the exit. The same formula applies to the cold fluid when the corresponding values are used. If heat leakage to the surroundings is negligible, the magnitude of the two transfer rates will be equal. This means that any heat lost by the hot fluid, is gained by the cold fluid. The overall conductance in Watts per Kelvin, is a measure of the heat transfer capacity of a heat exchanger. Let\'s analyze a particular geometry known as a counter-flow, tube-in-tube heat exchanger. In this design, the hot fluid flows in one direction inside a straight section of tube. The cold fluid flows in the opposite direction, in the annulus between the hot tube and a second outer tube. The average temperature difference driving heat transfer between the two streams in this geometry, is the log mean temperature difference, which can be calculated from the input and output temperatures of both streams. Using this model of heat exchanger operation, we can answer two different types of heat exchanger analysis problems. Rating and design. If the heat transfer rate and the log mean temperature difference are known, for example by experimental measurement, then the overall conductance can be calculated from the ratio of the two. For the purpose of design however, it is useful to predict what the overall conductance will be from the geometry and material properties of the heat exchanger. This can be done by finding the sum of thermal resistances between the two streams. For the tube-in-tube geometry, these resistances are determined by: convection in the hot fluid tube, conduction through the inner tube wall, and convection again in the cold fluid annulus. The inverse of this sum gives the overall conductance for the tube-in-tube counter-flow heat exchanger. Now that we have seen how to analyze the heat exchanger, let\'s test one in the laboratory.</td>
	</tr>
	<tr>
		<td width="99" valign="top">3</td>
		<td width="419" valign="top">Affix two plastic containers on opposite sides of the work surface to serve as hot and cold water reservoirs. If necessary, drill holes in the lids for inlet and outlet water lines, as well as the pump power cable. When you are finished, mount a small, submersible pump in each reservoir. Next, mount a water flow meter, or rotameter, vertically near each reservoir, and then use soft PVC tubing to connect the pump outlets to the flow meter inlets. Now, install two compression pipe tee fittings onto the outer cold water tube of the heat exchanger. Connect one flexible PVC tube, from the side port of the nearby tee fitting, to the outlet of hot flow meter. For the hot counter flow tube, cut a section of aluminum tubing equal in length to the heat exchanger, including the tee fittings on the end, and insert it into the assembly. Next, connect a soft plastic tube, from the compression fitting at other end of the heat exchanger assembly, to the hot water reservoir. Tighten the compression fittings to seal the soft plastic tubing around the aluminum tube. This will separate the hot flow, through the inner aluminum tube, from the outer cold flow. Connect the flexible PVC tube, from the side port on one tee fitting, to the cold flow meter outlet, and then connect a second tube to the side port of the other tee fitting returning to the cold water reservoir. Before continuing, confirm that the hot and cold stream inlets, to the heat exchanger, are on opposite ends. Drill a small hole through one side of the soft plastic tube near each inlet and outlet port of the heat exchanger. Gently insert a thermocouple probe into each port so that the probe tip is approximately in the center of the tube. Finally, use the epoxy, or similar adhesive, to seal the small gap in the tubes around the thermocouple probes against water leaks. When the epoxy is cured, connect all four thermocouple probes to a thermocouple reader. Now that the assembly is complete, you are ready to begin testing.</td>
	</tr>
	<tr>
		<td width="99" valign="top">4</td>
		<td width="419" valign="top">Fill the cold reservoir with room temperature tap water, and the hot reservoir with warm water. Turn on both water pumps and adjust the needle valves on the flow meters to increase the flow in both loops. Allow the water to circulate long enough to flush out any trapped air bubbles. Once the air bubbles are removed, adjust the flow rate in both loops to approximately 0.1 liters per minute. Wait a few minutes to allow the system to stabilize, and then record the inlet and outlet temperatures reported by the four thermocouple readings. Your thermocouple reader may have a hold function to freeze the current values while you are recording. Record five more sets of readings at these flow conditions. Repeat these measurements for flow rates of approximately 0.125 liters per minute, and 0.15 liters per minute. If the temperature difference between the hot and cold inputs drops below 5 degrees Celsius, refill the reservoirs with fresh hot and cold water. Now that the measurements are complete, let\'s take a look at the results.</td>
	</tr>
	<tr>
		<td width="99" valign="top">5</td>
		<td width="419" valign="top">You should have 18 sets of data, and for each set a measured volume flow rate. Note for these tests, the same flow rate, V-dot, is used for the hot and cold streams. First, use the density of water to convert each value of the volume flow rate to a mass flow rate. Now, calculate the rate of energy change for the hot and cold streams in each set by multiplying the mass flow rate, the specific heat of water, and the respective temperature differences. In the principle section, we assumed that the magnitude of these rates would be equal. Propagate uncertainties so that you can compare them. In most cases, the heat transfer rates match to within uncertainty; However, as the flow rate decreases, there is a trend towards increased heat loss from the hot fluid, as compared to the heat gained by the cold fluid. This is likely the result of heat loss to the surrounding environment; But since the effect is small, the average heat transfer rate can be used for the rest of the analysis. Next, lets evaluate the overall conductance of the heat exchanger, which can be determined from the measured heat transfer rate, and the log mean temperature difference. The overall conductance depends on material thermal conductivities, flow conditions, and the heat exchanger geometry. We anticipate that this value will not change significantly with flow rate for the low velocity laminar flows considered here. Use the measured temperatures with the equation given in the text to calculate the log mean temperature difference. Now, divide the average rate of energy change by the log mean temperature difference for each set to yield the overall conductance. As we anticipated, the overall conductance is relatively constant over the range of conditions that were tested, as evidenced by the small standard deviation over the data set. This result, however, is higher than the theoretical value predicted for steady fully developed laminar flow. If we assume developing flow at the inlets in both channels, and use suitable correction factors, the theoretical prediction will be higher than our measured result. In reality, flow in the inner channel will be partially developed before reaching the heat exchanger inlet, and this may explain the intermediate value of overall conductance. Now that we have analyzed the results of our simple heat exchanger, let\'s look at some typical applications.</td>
	</tr>
	<tr>
		<td width="99" valign="top">6</td>
		<td width="419" valign="top">Heat exchangers are employed in a wide variety of scenarios whenever heat transfer needs to be facilitated between two fluid streams. In many power generation plants, steam generator heat exchangers transfer heat from high temperature gas to produce high pressure steam to drive turbines. Down stream from these turbines, condenser heat exchangers reject heat from the low pressure steam, liquefying the fluid and allowing the cycle to operate continuously. In refrigerators, and air conditioning systems, evaporator heat exchangers absorb thermal energy from air in the conditioned space to maintain desired temperatures.</td>
	</tr>
	<tr>
		<td width="99" valign="top">7</td>
		<td width="419" valign="top">You\'ve just watched Jove\'s introduction to heat exchanger analysis. You should know understand the basic principles of heat exchangers, and how to analyze their performance experimentally and theoretically. Thanks for watching.</td>
	</tr>
</table>

In this experiment, a tube-in-tube counter-flow heat exchanger was fabricated, and its heat transfer capacity (UA) was experimentally measured (rated). The resulting performance was compared with results from a theoretical model. Modern heat exchangers often employ more sophisticated designs, with finned and enhanced surfaces to increase heat transfer intensity and optimized arrangements of fluid cross- and counter-flow. However, the basic concepts and parameters introduced here ...

heat exchanger analysis

Source: Alexander S Rattner and Christopher J Greer; Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA
Heat exchangers transfer thermal energy between two fluid streams, and are ubiquitous in energy systems. Common applications include car radiators (heat transfer from hot engine coolant to surrounding air), refrigerator evaporators (air inside refrigerator compartment to evaporating refrigerant), and cooling towers in power plants (condensing steam to evaporating water and ambient air). The objective of this experiment is to introduce experimental measurement (rating) and modeling procedures for heat exchangers.
In this experiment, a water-to-water tube-in-tube heat exchanger will be constructed, and evaluated. Temperature and flow rate measurements will be employed to determine the heat transfer rate (Q) and overall conductance (UA). The measured heat exchanger UA will be compared with predicted values for the geometry and operating conditions.

Table 1 - Measurements and derived LMTD and UA values for heat exchanger at hot and cold flow rates of 0.20 and 0.15 l min-1.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Hot and cold flow rates (l min-1)</td>
			<td>TH,in (&#176;C, &#177;0.25&#176;C)</td>
			<td>TC,out (&#176;C, &#17...

Source: Alexander S Rattner and Christopher J Greer; Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, ...

Heat exchangers are ubiquitous components in energy systems. Some common examples are car radiators and refrigerator evaporators. In both cases, the heat exchanger is facilitating the transfer of heat, from one stream of fluid to another. From these examples, it is clear that heat exchangers are important in a variety of systems; Primarily providing thermal management or transitions in thermodynamic cycles. An understanding of how to model and rate heat exchangers is important for optimizing designs and integrating heat exchangers into larger systems. This video will illustrate some principles of heat exchanger design and analysis, and then demonstrate those concepts on a simple tube-in-tube heat exchanger design. At the end, some common applications will be explored.A well designed heat exchanger should facilitate efficient, continuous heat transfer between two fluid streams, without allowing them to mix. As two fluid streams enter a heat exchanger, they are brought into close thermal contact across a physical barrier. Heat exchange is driven by a local temperature differences as the fluids progress, until the fluids reach the exit. The result is that the hotter of the two fluids entering the heat exchanger will exit with a reduced temperature, and the colder of the two with an increased temperature. During steady operation, the heat transfer rate of the hot fluid is determined by the mass flow rate and specific heat of the fluid, multiplied by the difference in temperature between the entrance and the exit. The same formula applies to the cold fluid when the corresponding values are used. If heat leakage to the surroundings is negligible, the magnitude of the two transfer rates will be equal. This means that any heat lost by the hot fluid, is gained by the cold fluid. The overall conductance in Watts per Kelvin, is a measure of the heat transfer capacity of a heat exchanger. Let's analyze a particular geometry known as a counter-flow, tube-in-tube heat exchanger. In this design, the hot fluid flows in one direction inside a straight section of tube. The cold fluid flows in the opposite direction, in the annulus between the hot tube and a second outer tube. The average temperature difference driving heat transfer between the two streams in this geometry, is the log mean temperature difference, which can be calculated from the input and output temperatures of both streams. Using this model of heat exchanger operation, we can answer two different types of heat exchanger analysis problems. Rating and design. If the heat transfer rate and the log mean temperature difference are known, for example by experimental measurement, then the overall conductance can be calculated from the ratio of the two. For the purpose of design however, it is useful to predict what the overall conductance will be from the geometry and material properties of the heat exchanger. This can be done by finding the sum of thermal resistances between the two streams. For the tube-in-tube geometry, these resistances are determined by: convection in the hot fluid tube, conduction through the inner tube wall, and convection again in the cold fluid annulus. The inverse of this sum gives the overall conductance for the tube-in-tube counter-flow heat exchanger. Now that we have seen how to analyze the heat exchanger, let's test one in the laboratory.Affix two plastic containers on opposite sides of the work surface to serve as hot and cold water reservoirs. If necessary, drill holes in the lids for inlet and outlet water lines, as well as the pump power cable. When you are finished, mount a small, submersible pump in each reservoir. Next, mount a water flow meter, or rotameter, vertically near each reservoir, and then use soft PVC tubing to connect the pump outlets to the flow meter inlets. Now, install two compression pipe tee fittings onto the outer cold water tube of the heat exchanger. Connect one flexible PVC tube, from the side port of the nearby tee fitting, to the outlet of hot flow meter. For the hot counter flow tube, cut a section of aluminum tubing equal in length to the heat exchanger, including the tee fittings on the end, and insert it into the assembly. Next, connect a soft plastic tube, from the compression fitting at other end of the heat exchanger assembly, to the hot water reservoir. Tighten the compression fittings to seal the soft plastic tubing around the aluminum tube. This will separate the hot flow, through the inner aluminum tube, from the outer cold flow. Connect the flexible PVC tube, from the side port on one tee fitting, to the cold flow meter outlet, and then connect a second tube to the side port of the other tee fitting returning to the cold water reservoir. Before continuing, confirm that the hot and cold stream inlets, to the heat exchanger, are on opposite ends. Drill a small hole through one side of the soft plastic tube near each inlet and outlet port of the heat exchanger. Gently insert a thermocouple probe into each port so that the probe tip is approximately in the center of the tube. Finally, use the epoxy, or similar adhesive, to seal the small gap in the tubes around the thermocouple probes against water leaks. When the epoxy is cured, connect all four thermocouple probes to a thermocouple reader. Now that the assembly is complete, you are ready to begin testing.Fill the cold reservoir with room temperature tap water, and the hot reservoir with warm water. Turn on both water pumps and adjust the needle valves on the flow meters to increase the flow in both loops. Allow the water to circulate long enough to flush out any trapped air bubbles. Once the air bubbles are removed, adjust the flow rate in both loops to approximately 0.1 liters per minute. Wait a few minutes to allow the system to stabilize, and then record the inlet and outlet temperatures reported by the four thermocouple readings. Your thermocouple reader may have a hold function to freeze the current values while you are recording. Record five more sets of readings at these flow conditions. Repeat these measurements for flow rates of approximately 0.125 liters per minute, and 0.15 liters per minute. If the temperature difference between the hot and cold inputs drops below 5 degrees Celsius, refill the reservoirs with fresh hot and cold water. Now that the measurements are complete, let's take a look at the results.You should have 18 sets of data, and for each set a measured volume flow rate. Note for these tests, the same flow rate, V-dot, is used for the hot and cold streams. First, use the density of water to convert each value of the volume flow rate to a mass flow rate. Now, calculate the rate of energy change for the hot and cold streams in each set by multiplying the mass flow rate, the specific heat of water, and the respective temperature differences. In the principle section, we assumed that the magnitude of these rates would be equal. Propagate uncertainties so that you can compare them. In most cases, the heat transfer rates match to within uncertainty; However, as the flow rate decreases, there is a trend towards increased heat loss from the hot fluid, as compared to the heat gained by the cold fluid. This is likely the result of heat loss to the surrounding environment; But since the effect is small, the average heat transfer rate can be used for the rest of the analysis. Next, lets evaluate the overall conductance of the heat exchanger, which can be determined from the measured heat transfer rate, and the log mean temperature difference. The overall conductance depends on material thermal conductivities, flow conditions, and the heat exchanger geometry. We anticipate that this value will not change significantly with flow rate for the low velocity laminar flows considered here. Use the measured temperatures with the equation given in the text to calculate the log mean temperature difference. Now, divide the average rate of energy change by the log mean temperature difference for each set to yield the overall conductance. As we anticipated, the overall conductance is relatively constant over the range of conditions that were tested, as evidenced by the small standard deviation over the data set. This result, however, is higher than the theoretical value predicted for steady fully developed laminar flow. If we assume developing flow at the inlets in both channels, and use suitable correction factors, the theoretical prediction will be higher than our measured result. In reality, flow in the inner channel will be partially developed before reaching the heat exchanger inlet, and this may explain the intermediate value of overall conductance. Now that we have analyzed the results of our simple heat exchanger, let's look at some typical applications.Heat exchangers are employed in a wide variety of scenarios whenever heat transfer needs to be facilitated between two fluid streams. In many power generation plants, steam generator heat exchangers transfer heat from high temperature gas to produce high pressure steam to drive turbines. Down stream from these turbines, condenser heat exchangers reject heat from the low pressure steam, liquefying the fluid and allowing the cycle to operate continuously. In refrigerators, and air conditioning systems, evaporator heat exchangers absorb thermal energy from air in the conditioned space to maintain desired temperatures.You've just watched Jove's introduction to heat exchanger analysis. You should know understand the basic principles of heat exchangers, and how to analyze their performance experimentally and theoretically. Thanks for watching.

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Mechanical Engineering

measuring heat transfer in a tube exchanger

Heat exchangers move thermal energy between two fluid streams and are common in energy systems. They appear in car radiators, refrigerator evaporators, and cooling towers in power plants. In each case, heat moves from one fluid to another, either directly or through a surface.

This experiment focuses on a water-to-water tube-in-tube heat exchanger. The setup is built and then tested with temperature and flow rate measurements. These measurements are used to find the heat transfer rate, or Q, and the overall conductance, or UA.

The measured UA is then compared with predicted values for the same geometry and operating conditions. This comparison helps connect experimental data with heat exchanger models. It also shows how rating procedures are used to evaluate real heat exchangers.

Measuring Heat Transfer in a Tube Exchanger

measuring-heat-transfer-in-a-tube-exchanger

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Boat stability depends on hull shape and internal mass distribution. A stable vessel can self-right after it is rolled to one side by an outside force. Careful hull design helps seagoing vessels stay stable with a low draft, which is the submerged depth of the hull. That can improve maneuverability and reduce drag. This experiment uses a model boat with an adjustable center of mass, which represents different cargo loadings. The boat is also modified for automated tracking of its roll angle.

propulsion and thrust

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Propulsion systems create thrust by speeding up a surrounding fluid or high-temperature combustion products. Aircraft, rockets, and ships all use this basic idea. When the fluid leaves at high velocity, conservation of momentum produces an effective force on the vehicle. Thrust is often checked with static thrust tests. In these tests, the propulsion system is fixed to an instrumented mount, and the holding force on the mount is measured as thrust. This setup lets the system run while the...

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Measuring Pressure Drop in Pipe Components

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Vapor compression refrigeration shows how refrigerators, freezers, air-conditioning systems, and heat pumps remove heat. It is the dominant refrigeration technology used in many everyday devices. In this cycle, cooling happens when refrigerant evaporates at low pressure. The absorbed thermal energy is then released to the surroundings when the refrigerant condenses at high pressure. The compressor is the part that raises the working fluid from low pressure to high pressure. Mechanical work is...

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measuring turbulent flows

Hot-Wire Analysis of a Turbulent Jet

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visualization of flow past a bluff body

Hydrogen Bubble Flow Around a Cylinder

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Measuring Jet Force on an Inclined Plate

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mass-conservation-and-flow-rate-measurements

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mechanical engineering

This collection introduces a range of concepts that are essential for understanding and designing mechanical systems. Each video examines a specific topic and describes fundamental analytical methods commonly employed to understand physical behaviors.

Measure heat transfer in a water-to-water tube-in-tube exchanger using temperature and flow rate data, then compare measured UA with predicted values.

Measuring Heat Transfer in a Tube Exchanger | JoVE K12

Texas Essential Knowledge and Skills

Physics

PHYS.2

PHYS.2.D

Chemistry and Physics

IPC.2

IPC.2.D

Overview

Principles of Heat Exchanger Analysis

Constructing the Apparatus

Performing the Experiment

Results

Applications

Summary

Quantifying Heat

Thermal Energy&#160;

Microscopically, thermal energy is the kinetic energy associated with the random motion of atoms and molecules. Temperature is a ...

Temperature and Thermal Equilibrium

Heat and temperature are essential concepts for everyone every day. The study of heat and temperature is part of an area of physics known as ...

Types of Kinetic Energy

The amount of kinetic energy of an object depends on its mass and speed. Consider two balls of different masses rolling down an inclined plane at the same ...

Heat Flow and Specific Heat

Heat is a type of energy transfer that is caused by a temperature difference, and it can change the temperature of an object. Since heat is a form of ...

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Kinetic Molecular Theory: Molecular Velocities, Temperature, and Kinetic Energy

The kinetic molecular theory qualitatively explains the behaviors described by the various gas laws. The postulates of this theory may be applied in a ...

Constant Pressure Calorimetry

Calorimetry is a technique used to measure the amount of heat involved in a chemical or physical process or to measure the heat transferred to or from a ...

Contrast the concepts of temperature and heat flow in macroscopic and microscopic terms. Understand that thermal energy is a form of energy and temperature is a measure of average kinetic energy of a particle. EXPLANATION: Students have been exposed to the types of energy (potential, kinetic, thermal, and chemical) and energy transfer (working, heating, and radiating) in the sixth grade. At that time, students classified energy types in systems and transformations. The focus in Chemistry 1 should be on understanding that measuring the temperature of a system is a way to quantify the thermal energy (average kinetic energy) of the particles in that system. Heating is a mechanism that transfers energy to or from a system. Students should also explore absolute vs relative scales of temperature mechanisms. Students should recognize that energy will always flow from objects with greater thermal energy to areas with lesser thermal energy, but rates of energy flow are a property of the materials being heated. The degree to which the temperature changes as an object is also a physical property of a material. Activities may include collecting or analyzing pressure vs temperature data, then considering why a graph of collected data does not pass through the origin. (Heat capacity and conductivity will only be assessed qualitatively.)

CHEM1.PS3.1

Heating and Cooling Curves

When a substance&#8212;isolated from its environment&#8212;is subjected to heat changes, corresponding changes in temperature and phase of the substance ...

Calorimetry

When objects at different temperatures are placed in contact with each other but isolated from everything else, they attain thermal equilibrium. A ...

Differential Scanning Calorimetry

Source: Danielle N. Beatty and Taylor D. Sparks, Department of Materials Science and Engineering, The University of Utah, Salt Lake City, UT
Differential ...

Constant Volume Calorimetry

Calorimeters are useful to determine the heat released or absorbed by a chemical reaction. Coffee cup calorimeters are designed to operate at constant ...

Conservation of Energy

The terms &#39;conserved quantity&#39;&#160;and &#39;conservation law&#39;&#160;have specific scientific meanings in physics, which differ from the ...

Draw and interpret heating and cooling curves and phase diagrams. Analyze the energy changes involved in calorimetry by using the law of conservation of energy quantitatively (use of $q=mc\Delta T)$ and qualitatively. EXPLANATION: This is one of two standards where students are to investigate changes in a specific types of energy: In this case, thermal energy and phase energy. Starting as early as kindergarten, students are introduced to solid and liquid phases of matter. By third grade, students are considering the particulate nature of matter to discuss physical properties of the different phases. In fifth grade, students discuss phase changes from the perspective of the arrangement of particles. Chemistry 1 is the first time that students make a connection between phase changes and energy changes. Students commonly struggle with the idea that substances can be heated, but that heating does not always result in a change in temperature. Models of phase energies associated with the arrangement of particles aid in dispelling these misconceptions. Comparisons should identify similarities in energies in solids and liquids as compared to vastly different energy in gases. Discussions of heat of fusion/vaporization and calculations to enrich these discussions are appropriate. Finally, students should be able to quantify relationships in which heating creates a change in the thermal energy of a sample. Activities may include determining energy released when an object is burned to change the temperature of a substance in a closed system. (Note that this standard is limited to calculations of energy associated with changes in thermal energy, and not energies associated with phase transformations.)

Energy Transfer in Chemical Reactions

Chemical reactions require sufficient energy to cause the matter to collide with enough precision and force that old chemical bonds can be broken and new ...

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Energy Diagrams, Transition States, and Intermediates

Free-energy diagrams, or reaction coordinate diagrams, are graphs showing the energy changes that occur during a chemical reaction. The reaction ...

Energy Basics

Chemical reactions, such as those that occur when you light a match, involve changes in energy as well as matter.

Chemical changes and their accompanying ...

endergonic-and-exergonic-reactions-in-the-cell

Endergonic and Exergonic Reactions in the Cell

If energy releases during a chemical reaction, then the resulting value&#160;will be a negative number. In other words, reactions that release energy have ...

Thermochemical Equations

For a chemical reaction (the system) carried out at constant pressure &ndash; with the only work done caused by expansion or contraction &ndash; the ...

Activation Energy

Activation energy is the minimum amount of energy necessary for a chemical reaction to move forward. The higher the activation energy, the slower the rate ...

Bond Energies and Bond Lengths

Stable molecules exist because covalent bonds hold the atoms together. The strength of a covalent bond is measured by the energy required to break it, ...

Introduction to Chemical Reactions

All chemical reactions begin with a reactant, the general term for one or more substances entering the reaction. Sodium and chloride ions, for example, ...

bond-dissociation-energy-and-activation-energy

Bond Dissociation Energy and Activation Energy

Bond energy is the energy required to break a bond homolytically. These values are usually expressed in units of kcal/mol or kJ/mol and are referred to as ...

Distinguish between endothermic and exothermic reaction by constructing potential energy diagrams and explain the differences between the two using chemical terms (e.g. activation energy). Recognize when energy is absorbed or given off depending on the bonds formed and bonds broken. EXPLANATION: This is one of two standards where students are to investigate changes in a specific type of energy: In this case, chemical energy. Students should recognize that the formation of bonds releases energy, while the breaking of bonds is endothermic. Synthesis reactions to form metal oxides can provide observations if carried out taking proper precautions. Clear changes to masses and physical properties provide evidence of a reaction. (Specific discussions of enthalpy of formation are beyond the scope of this standard, but the topic may be useful for enrichment discussions about reactions where bonds are both broken and formed.)

CHEM1.PS3.3

Conservation of Energy: Application

When solving problems using the energy conservation law, the object (system) to be studied should first be identified. Often, in applications of energy ...

Conservation of Energy Approach to System Analysis

Source: Ricardo Mejia-Alvarez and Hussam Hikmat Jabbar, Department of Mechanical Engineering, Michigan State University, East Lansing, MI
The purpose of ...

What is Energy?

The universe is composed of matter in different forms, and all forms of matter contain energy. &nbsp;The different forms of energy on Earth originate from ...

First Law of Thermodynamics

Energy Conservation

Energy can be converted from one form into another, but all of the energy present before a change occurs always exists in some form ...

Conservation of Mechanical Energy

The mechanical energy E of a system is the sum of its potential energy U and the kinetic energy K of the objects within it. What happens to this ...

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Energy and Work

Source: Ketron Mitchell-Wynne, PhD,&#160;Asantha Cooray, PhD, Department of Physics &#38; Astronomy, School of Physical Sciences, University of ...

Conservative Forces

According to the law of conservation of energy, any transition between kinetic and potential energy conserves the total energy of the system. Hence, the ...

Non-conservative Forces

Non-conservative forces are dissipative forces such as friction or air resistance. These forces take energy away from a system as it progresses. Unlike ...

Energy Diagrams - I

The dynamics of a mechanical system can be easily understood by interpreting a potential energy diagram. Since energy is a scalar quantity, the ...

Energy Diagrams - II

Energy diagrams are important to understand the dynamics of a system. The topology of an energy diagram helps illustrate the equilibrium points of the ...

Analyze energy changes to explain and defend the law of conservation of energy. EXPLANATION: Standards PS3.2 and PS3.3 identify the energy types most commonly associated with chemical reactions and build on sixth grade discussions of energy storage and transfer types. In Chemistry 1, students will synthesize an understanding of law of conservation of energy by being able to distinguish system from surroundings, and recognizing that tracking energy requires both the system and surrounding energies to be considered. Students can consider interactions such as a beverage warming/cooling, a refrigerator cooling food, the function of Freon in cooling systems, or a car's cooling system as examples where multiple systems interact.

CHEM1.PS3.4

Measuring Heat Transfer in a Tube Exchanger

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