Aerospace Engineering Lab 1 Sem2 0809

Semester 2, 08/09

AEROSPACE ENGINEERING LAB 1 (MEC 2700)

LABORATORY MANUAL

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

1

Table of Contents Page Experiment 1: Thermal and Electrical Conductivity of Metals

1

Experiment 2: Heat Pump

8

Experiment 3: Heat Conduction

13

Experiment 4: Free and Forced Convection

16

Experiment 5: Thermal Radiation

19

Tables for Data Collection & Calculation

22

Semester 2, 08/09

Experiment 1 – Thermal and Electrical Conductivity of Metals C) BACKGROUND If a temperature difference exists between different locations of a body, heat conduction occurs. In this experiment there is a one-dimensional temperature gradient along a rod. The quantity of heat dQ transported with time dt is a function of the cross-sectional area a and the temperature gradient dT/dx perpendicular to the surface.

(1) λ is the heat conductivity of the substance. The temperature distribution in a body is generally a function of location and time and is in accordance with the Boltzmann transport equation (2) Where r is the density and c is the specific heat capacity of the substance. After a time, a steady state

(3)

is achieved if the two ends of the metal rod having a length l are maintained at constant temperatures T1 and T2, respectively, by two heat reservoirs. Substituting equation (3) in equation (2), the following equation is obtained:

(4)

D) OBJECTIVE i) ii)

To determine the thermal conductivity of copper, this is determined in a constant temperature gradient from the calorimetrically measured heat flow. The electrical conductivity of copper and aluminium is determined.

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

1

Semester 2, 08/09

E) EQUIPMENT Calorimeter vessel, 500 ml Calor. vessel w. heat conduct. conn. Heat conductivity rod, Cu Heat conductivity rod, Al Magn. stirrer, mini, controlable Heat conductive paste, 50 g Gauze bag Rheostat, 10 Ohm , 5.7 A Immers.heater, 300 W, 220-250VDC/AC Temperature meter digital Temperature probe, immers. type Surface temperature probe Stopwatch, digital, 1/100 sec. Tripod base -PASSBench clamp -PASSSupport rod -PASS-, square, l 630 mm Support rod -PASS-, square, l 1000 mm Universal clamp Right angle clamp -PASSSupporting block 1053105357 mm Glass beaker, short, 400 ml Multitap transf., 14VAC/12VDC, 5A Digital multimeter Universal measuring amplifier Connecting cord, 500 mm, red Connecting cord, 500 mm, blue

F) PROCEDURE Part A – Heat Capacity of the Calorimeter 1. 2. 3. 4.

Weigh the lower calorimeter at room temperature Measure and record the room temperature. Prepare hot water and record its temperature. Pour the hot water into the lower calorimeter and immediately record the temperature readings of the hot water in the calorimeter every 10 seconds for 5 minutes. *Note: There will be an immediate increase then a decrease in temperature as illustrated in Figure 3. 5. Reweigh the calorimeter to determine the mass of water. Part B – Ambient Heat

1. The calorimeter is then put under running tap water in order to get it back to room temperature. 2. The calorimeter is then filled with ice water. With the assistance of ice, obtain water with a temperature of 0oC. 3. When a temperature of 0oC is obtained, remove all the pieces of ice and record the temperature every minute for 30 minutes. 4. Weigh the calorimeter to determine the mass of water.

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

2

Semester 2, 08/09

Figure 1 Part C – Thermal Conductivity 1. The setup is as shown in Figure 1. In this experiment, the difference in temperature between the upper and lower mediums is monitored, as well as the temperature of the water in the lower calorimeter. 2. Fill the lower calorimeter with ice water. With the aid of ice, obtain a temperature of 0oC. 3. When a temperature of 0oC is obtained, pour hot water in the upper calorimeter. Ensure that the upper calorimeter is well filled with hot water. Place its cover on. 4. Keep the temperature of water in lower calorimeter water at 0oC with the help of ice, until the difference in temperature between two points on the rod, is steady. 5. When a constant temperature gradient is obtained, remove all the ice in the lower calorimeter and begin taking readings of the difference in temperature between upper and lower mediums and the temperature of the water in the lower calorimeter. Readings should be taken every 30 seconds for 5 minutes. 6. Weigh the lower calorimeter to determine the mass of water.

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

3

Semester 2, 08/09

Figure 2 Part D – Electrical Conductivity 1. The setup is as shown in Figure 2. The metal rod in the setup is copper. 2. Ensure that the voltage on the variable transformer is set to 6V. 3. The amplifier must be calibrated to 0 in a voltage-free state to avoid a collapse on the output voltage. Select the following amplifier settings: Input Low Drift Amplification 104 Time Constant 0 4. Set the rheostat to its lowest value (labeled using a green marking on the rheostat) and slowly decrease the value during the experiment. 5. Collect readings of current and voltage for six rheostat settings. 6. Repeat the experiment using the aluminium rod.

G) PRE-LAB 1. 2. 3. 4. 5.

What is constant temperature gradient? What is the expected graph for part A? What are the literature value for electrical and thermal conductivity of aluminium and copper? Which is a better conductor? Aluminium or copper? Should the ambient heat increase or decrease with time?

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

4

Semester 2, 08/09

H) REPORT Part A – Heat Capacity of the Calorimeter 1. From the results obtained, plot a graph of temperature vs. time. 2. The temperature of the mixture, ϑm , is determined from extrapolating the plotted curve, as sketched in figure below. The straight line parallel to temperature axis was drawn such that the shaded parts are equal in area. Illustrate how you obtained θm.

Figure 3

ϑu = Temperature of the surrounding atmosphere ϑ1 = Initial temperature ϑm = Temperature of mixture 3. Calculate the heat capacity of the calorimeter using the following equation:

C = c w ⋅ mw ⋅

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

ϑw − ϑM ϑM − ϑR

5

Semester 2, 08/09

where cW = Specific heat capacity of water

mW = Mass of water

ϑW = Temperature of the hot water ϑ M = Mixing temperature ϑ R = Room temperature * Remember : ∆ T = 1K = 1oC Part B – Ambient Heat 1. Calculate the addition of heat from the surroundings for each minute.

ΔQ = (cW ⋅ mW + C ) ⋅ ΔT where ΔT = T – T0 T0 = Temperature at time t = 0 cW = Specific heat capacity of water

mW = Mass of water C = heat capacity of the calorimeter 2. Draw a graph of heat from surroundings vs time. 3. Calculate the slope for the graph which will give you dQ/dtambient. Part C – Thermal Conductivity 1. Calculate Q and draw the graph of Q vs t. Find the slope of this graph, which will give you

dQ ambient.+ metal. dt dQ 2. Calculate metal, given that: dt dQ dQ dQ metal = ambient.+ metal ambient dt dt dt 3. Given the length of the rod as 31.5 cm and the area as 4.91x10-4 m2, calculate the heat conductivity of the rod, λ.

dQ ∂T = −λ A ⋅ ∂x dt 4. Calculate the average heat conductivity of the rod and compare to literature.

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

6

Semester 2, 08/09

Part C – Electrical Conductivity 1. Calculate the electrical conductivity using the following equation:

σ=

l A⋅R

2. Calculate the error of your results when compared to literature.

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

7

Semester 2, 08/09

Experiment 2 - Heat Pump A. BACKGROUND Pressures and temperatures in the circulation of the electrical compression heat pump are measured as a function of time when it is operated as a water-water heat pump. The energy taken up and released is calculated from the heating and cooling of the two water baths. When it is operated as an air-water heat pump, the coefficient of performance at different vaporizer temperatures is determined. The Mollier (h, log p) diagram, in which p is the pressure and h the specific enthalpy of the working substance, is used to describe the cyclic process in heat technology. Fig. 1 shows an idealised representation of the heat pump circuit. The curve running through the critical point K delineates the wet vapour zone in which the liquid phase and gas phase coexist. In this zone the isotherms run parallel to the h axis. Starting from point 1, the compressor compresses the working substance up to point 2; in the ideal case this action proceeds without an exchange of heat with the environment, i.e. isentropically (S = const.). On the way from point 3 useful heat is released and the working substance condenses. Then the working substance flows through the restrictor valve and reaches point 4. In an ideal restricting action the enthalpy remains constant. As it passes from point 4 to point 1, the working substance takes up energy from the environment and vaporises. The specific amounts of energy q0 and q taken up and released per kg and the specific compressor work w required can be read off directly as line segments on the graph. q0 = h1 – h3 q = h2 – h3 w = h2 – h1 For evaluation purposes the data for the working substance R 134a in the wet vapour zone are set out in Table 1.

Figure 1: h, log p diagram of a heat pump, ideal curve.

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

8

Semester 2, 08/09

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

9

Semester 2, 08/09

B. OBJECTIVE a. Water heat pump: To measure pressure and temperature in the circuit and in the water reservoirs on the condenser side and the vaporizer side alternately. To calculate energy taken up and released, also the volume concentration in the circuit and the volumetric efficiency of the compressor. b. Air-water heat pump: To measure vaporizer temperature and water bath temperature on the condenser side under different operating conditions on the vaporizer side, ie. Natural air, cold blower and hot blower. c. To determine the electric power consumed by the compressor and calculate the coefficient of performance.

C. EQUIPMENT Heat pump, compressor principle Lab thermometer, -10…+100C Lab thermometer, w. stem, -10…+110C Heat conductive paste, 50 g Hot-/Cold air blower, 1000 W Stopwatch, digital, 1/100 sec Tripod base -PASSSupport rod -PASS-, square, l 250 mm Universal clamp with joint Glass beaker Glass rod

Figure 1

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

10

Semester 2, 08/09

D. PROCEDURE Part A – Water-water Heat Pump 1. Pour 4.5L of water into the two water reservoirs. 2. Record all the initial pressures and temperatures before switching on the heat pump. 3. Start the stopwatch at the same time the heat pump is switched on. Record the power reading and the pressure and temperatures on both the vaporizer and condenser side every minute for 20 minutes. Part B – Air-water Heat Pump i. ii. iii. iv. v.

Remove the water reservoir on the vaporizer side and dry the heat exchanger coils. Obtain a temperature of 20oC for the 4.5L water on the condenser side. Record all the initial pressures and temperatures before switching on the heat pump. Start the stopwatch at the same time the heat pump is switched on. Record the power reading, and the temperatures at the vaporizer outlet and condenser water temperature, every minute for approximately 20 minutes. Repeat steps ii to iv but with a hot blower and a cold blower approximately 30cm away.

E. PRE-LAB 1. What is a heat pump? How does it work? 2. What everyday items around us use this system?

F. REPORT Part A – Water-water Heat Pump i.

Mass of water: a. condenser = ____________ b. vaporizer = _____________

ii.

Plot a graph of temperature vs time for all inlet and outlet. You can plot on the same graph for all inlet and outlet.

iii.

Calculations at t = 10mins a. Vaporizer heat flow,

Q&

b. Condenser heat flow, c.

o

Q&

= c ⋅ mw ⋅

Δθ 2 Δt

= c ⋅ mw ⋅

Δθ1 Δt

Average compressor power, P

d. Performance at the condenser side, ε =

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

Q& P 11

Semester 2, 08/09

Q& 0 e. Volume flow at the vaporizer side, V& = v ⋅

h1 − h3

(v = specific volume of the vapour) The values of v, h1 and h3 are from Table 1. f.

Geometrical volume flow, V&g = V g ⋅ f Given Vg = 5.08 cm3 f = 1450 min-1

g. Volumetric efficiency of the compressor, λ =

V& Vg

Part B – Air-water Heat Pump i. Plot a graph of temperature versus time for all the results. ii. Calculations at t = 10mins: 1. Calculate the average vaporizer temperature. 2. Calculate the condenser heat flow. 3. Calculate the average compressor power. 4. Calculate the performance. iii. Compare the results for all the conditions and discuss.

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

12

Semester 2, 08/09

Experiment 3 – Heat Conduction A. BACKGROUND Thermal conduction is a mode of heat transfer which occurs in a material due to the presence of temperature gradient. It is a transfer of energy from the more energetic particles to the adjacent less energetic particles. Generally, heat is defined as energy transfer due to the temperature gradients or difference between two points. Heat energy can be transferred in three modes, which are conduction, convection, and radiation. One of the most common heat transfer modes, which is conduction heat transfer, is defined as heat transferred by molecules that travel a very short distance (~0.65 m) before colliding with another molecule and exchanging energy. In this experiment, both linear and radial conduction heat transfer methods are studied. The entire system (insulated heater/specimen, air and laboratory enclosure) are at room temperature initially (t = 0). The heater generates uniform heat flux as switched on. For linear conduction, an electrical heating element, which comprises of a heat input section fabricated from brass fitted with an electrical heater, is bonded to one end of a metal rod (heat source). Another end of the rod, which is also made of brass, is exposed to heat discharge (heat sink). The outer surface of the cylindrical rod is well insulated; thus yielding one-dimensional linear heat conduction in the rod once the heating element is switched on. Thermocouples are embedded in the rod, along its centerline. A simple mimic diagram for heat conduction along a well-insulated cylindrical rod is shown as below: Insulation Imposed Hot Th Temperature (Heat Source)

Ac

qx

Tc, Imposed Cold Temperature (Heat Sink) x

dx

L For radial conduction, the electrical heating element is bonded to the center part of a circular brass plate (heat source). The cooling water flows through the edge of the plate that acts as a heat sink for heat discharge. The other surfaces of the plate are well insulated to simulate radial heat conduction from the plate center to its edge when the heating element is switched on. The brass plate has a radius, rplate = 60 mm and thickness, t = 3.2 mm. Thermocouples are embedded in the circular plate. A simple mimic diagram for heat conduction along a well-insulated circular plate is shown as below: y Imposed cold temperature (Heat Sink)

r t Imposed hot temperature (Heat Source)

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

13

Semester 2, 08/09

B. OBJECTIVE The aim of the experiment is to study the Fourier’s Law on linear and radial conduction heat transfer, as well as to illustrate the transfer of heat by conduction in solid materials while varying the parameters affecting conduction. C. EQUIPMENT The Heat Conduction Study Bench D. PROCEDURE Part A – Linear Conduction along a Homogeneous and Composite Bar 1. Connect the power cable for the Cylindrical Test Unit to the display unit. 2. Clamp the 25mm diameter brass specimen into the intermediate section of the linear module. Apply thermal paste onto the surfaces to ensure proper contact. 3. Insert the thermocouples into their respective slots (follow the labeling of 1 to 8). 4. Turn on the equipment by turning the main power knob clockwise. 5. Set the water flow to 1.4 L/min. 6. Looking at the display, press ESC (top right button) and then press F1 to choose the Cylindrical Test Unit. 7. Switch on the heater by pressing the heater switch and set the power to 10W by turning the heater adjust knob and viewing the power on the display unit. The heater knob may be locked by flicking the small black lever at the side of the knob downwards. 8. Wait till steady state by monitoring the temperatures of the thermocouples on the display unit. 9. Record the temperatures of all the thermocouples as well as the thermal conductivity obtained. 10. After recording the results, switch off the heater before changing the specimen. 11. Repeat steps 2 to 10 using the 25mm diameter stainless steel and 16mm diameter brass specimen. * Note : During the assembly of the intermediate sections, ensure that the contact surfaces are properly mated. Use the heat transfer compound provided to ensure good contact. Part B – Radial Conduction along Circular Metal Plate 1. 2. 3. 4. 5.

Connect the power cable for the Radial Test Unit to the display unit. Insert the thermocouples into their respective slots (follow the labeling of 1 to 6). Ensure that the water flow is 1.4 L/min. To exit from the previous session, press ESC and then press F2 to go to the Radial Test Unit. Switch on the heater by pressing the heater switch and set the power to 10W by turning the heater adjust knob and viewing the power on the display unit. The heater knob may be locked by flicking the small black lever at the side of the knob downwards. 6. Wait till steady state by monitoring the temperatures of the thermocouples on the display unit. 7. Record the temperatures of all the thermocouples as well as the thermal conductivity obtained. 8. After recording the results switch off the heater. DO NOT SWITCH OFF THE POWER! The power may only be switched off after T1 reads less than 50oC.

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

14

Semester 2, 08/09

E. PRE-LAB 1. 2. 3. 4.

What is conduction? What should the temperature profile look like for linear and radial conduction? What is Fourier’s Law? What is the equation needed to calculate thermal conductivity for linear and radial conduction?

F. REPORT 1. Plot the temperature profile for both models as a function of distance. 2. By using fourier’s law, calculate the thermal conductivity for each specimen used. 3. Calculate the error between the calculated result and the result obtained during the experiment.

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

15

Semester 2, 08/09

Experiment 4 – Free and Forced Convection

A. BACKGROUND

Convection is a mode of energy transfer between a solid surface and the adjacent fluid in motion. Convection heat transfer involves the combined effects of conduction and fluid motion. The transfer of heat by convection plays an important role in many areas of our daily life as well as of industry. Heat transfer by convection between a surface and the surrounding fluid can be increased, by attaching thin strips of metal fins to the surface. When heat transfer takes place by convection from both interior and exterior surfaces of a tube or a plate, generally fins are used on the surfaces where the heat transfer coefficients are low. Heat transfer by simultaneous conduction and convection, whether free or forced, forms the basis of most industrial heat exchangers and related equipment. The measurement and prediction of heat transfer coefficients for such circumstances is achieved in the free and forced convection heat transfer apparatus by studying the temperature profiles and heat flux in an air duct with associated flat and extended transfer surfaces.

In this experiment, students are required to perform free and force convection heat transfer using different type extended surface plate.

A heated surface dissipates heat to the surrounding fluid primarily through a process called convection. Heat is also dissipated by conduction and radiation, however these effects are not considered in this experiment. Air in contact with the hot surface is heated by the surface and rises due to reduction in density. The heated air is replaced by cooler air, which is in turn heated by the surface, and rises. This process is called free convection.

In free convection small movements of air generated by this heat limit the heat transfer rate from the surface. Therefore more heat is transfer if the velocity is increase over the heated surface. This process of assisting the movement of air over the heated surface is called forced convection. A heated surface experiencing forced convection will have a lower surface temperature than that of the same surface in free convection, for the same power input.

Convection heat transfer from an object can be improved by increasing the surface area in contact with the air. In practical it may be difficult to increase the size of the body to suit. In these circumstances the surface area in contact with the air may be increased by adding fins or pins normal to the surface. These features are called extended surfaces. A typical example is the use of fins on the cylinder and head on an air-cooled petrol engine. The effect of extended surfaces can be demonstrated by comparing finned and pinned surfaces with a flat under the same conditions of power input and airflow Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

16

Semester 2, 08/09

B. OBJECTIVE The experiment aims to illustrate the transfer of heat by convection both naturally and by force. The parameters that affect the heat transfer are also explored and comparisons between different types of solid surfaces are made. -

To demonstrate the use of extended surfaces to improve heat transfer from a surface. To demonstrate convection heat transfer by using different type of extended surface. To see the effect of different flow velocity on the convection heat transfer. To determine the temperature distribution along an extended surface.

C. EQUIPMENT 1. 2. 3. 4.

G.U.N.T. WL350 TEST UNIT, FREE AND FORCED CONVECTION Heater inserts – flat plate, cylinder and fin Thermocouple Air measurement probe

Sketch diagram of Convention Heat Transfer Rig

D. PROCEDURE 1. Insert the flat plate heater insert. (MAKE SURE THAT THE HEATER POWER SUPPLY IS FIRST SWITCHED OFF BEFORE REPLACING THE HEATER INSERT. BEWARE OF HOT SURFACES!!!) 2. Switch on the equipment (press the black switch behind the measuring unit). Ensure that the heater and fan is switched off. Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

17

Semester 2, 08/09

3. Set the heater to no. 7 and turn it on. 4. Allow sufficient time to achieve a steady state condition before taking the readings of temperature as shown below: a. Inlet air temperature, Tin at TP1 (using a probe) b. Outlet air temperature, Tout at TP12 (using a probe) c. Temperatures T2, T3, T4 and T5 (using a thermocouple) *Note - Ensure that the probe is reading the temperature at center of the equipment. - The thermocouples should not be touching the extended surface. 5. Set the fan to no. 8 and switch on the fan. 6. Allow sufficient time to achieve a steady state condition before taking the readings of temperature as shown below: a. Inlet air temperature, Tin at TP1 (using a probe) b. Outlet air temperature, Tout at TP12 (using a probe) c. Temperatures T2, T3, T4 and T5 (using a thermocouple) *Note - Ensure that the probe is reading the temperature at center of the equipment. - The thermocouples should not be touching the extended surface. 7. Switch off the heater and fan before changing the extended surface. 8. Repeat steps 1 to 7 for the fin and cylinder heater inserts. 9. Remember to measure the distance of the access holes from the back plate of the heater inserts.

E. PRE-LAB 1. What is convection? 2. How does surface area affect conduction? 3. How does fluid velocity affect conduction?

F. REPORT 1. Plot graphs of temperature against distance for each plate. Explain on the graphs plotted. 2. Comment on the correlation between total surface area of the heat exchanger and the temperature obtained. Which of the extended surfaces has greater surface area? 3. Comment on the correlation between air velocity and the temperatures obtained.

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

18

Semester 2, 08/09

Experiment 5 – Thermal Radiation A. BACKGROUND Thermal radiation is a transfer of heat by electromagnetic waves with its related laws being different to those for conduction and convection. No medium of transfer is required as exemplified by the energy of the sun reaching the earth and all bodies at temperatures above absolute zero emit thermal radiation. Two most important physical laws on thermal and optical radiation are Stefan Boltzmann’s and Lambert’s distance laws. As commonly known heat transfer due to a temperature difference. Heat can be transferred in three different ways, which are known as conduction, convection and radiation. Any object that is hot gives off light known as Thermal Radiation. The hotter an object is, the more light it emits. And, as the temperature of the object increase, it emits most of its light at higher and higher energies. (Higher energy light means shorter wavelength light.) In general, the net rate of energy transfer by thermal radiation between two surfaces involves complicated relationships among the properties of the surface, their orientations with respect to each other, the extent to which the intervening medium scatters, emits and absorbs thermal radiation and other factors In these experiments, we will prove some fundamental law relating to radiation. Inverse square law of heat The total energy dQ from an element dA can be imagined to flow through a hemisphere of radius r. A surface element on this hemisphere dA1 lies on a line making an angle with the normal and the solid angle subtended by dA1 at dA is dw = dA1/r2 If the rate of flow of energy through dA1 is dQ then dQ = i dwdA where i is the intensity of radiation in the direction

Figure 6.1 Solid Angle The Stefan-Boltzmann Law states that : q b= (Ts4 –Ta4) Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

19

Semester 2, 08/09

Where

qb = energy emitted by unit area of a black body surface (Wm-2) (Note: Energy emitted by surface =3.040 X reading from radiometer R – refer to Radiometer Data sheet for explanation) = Stefan-Boltzmann constant equal to 5.67 x 10-8 (Wm-2K-4) Ts = Source temperature and surrounding = black plate temp. (K) Ta = Temperature of radiometer and surrounding = room temp.(K)

B. OBJECTIVE The experiment aims to demonstrate the most important physical laws on thermal and optical radiation. C. EQUIPMENT Thermal Radiation Study Unit WL360 D. PROCEDURE Part A – Stefan-Boltzmann Law 1. Place the radiometer 150mm from the heat source. 2. Switch on the radiometer and observe and record the background readings i.e. radiation and temperature. The on switch is situated behind the measuring unit. (Ensure that the heater is switched off) 3. Ensure that the power cable for the heater is connected. Switch on the heater switch and set the power regulator to 5. 4. Record the temperature and radiometer readings for every 10oC increments of increasing temperature up to 100oC. Part B – Lambert’s Distance Law 1. Leave the heater on from the Part A. 2. Place the radiometer at a distance of 1000mm from the heat source. 3. Wait for steady state then record the radiometer reading and the distance from the heat source of the radiometer along the horizontal track for each 100mm from 1000mm. 4. After completing the experiment, switch off the heater. Part C – Lambert’s Direct Law (Cosine Law) 1. Mount the luxmeter at a separation of L = 400mm from the light source. Ensure that the luxmeter is connected to the measuring amplifier. 2. Connect the power cable to the light source. 3. Note the background illuminance. 4. Mount the light source in position φ = 0o, switch on the power and set the power regulator to setting no. 9. 5. Record the illuminance, E in Lux and repeat the procedure with increasing angle of incidence, φ in steps of 10o (0o to 900). Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

20

Semester 2, 08/09

E. PRE-LAB 1. What are the three laws to be demonstrated in this experiment? Explain each one in detail. 2. What is a log-log graph paper? If possible, bring one. F. REPORT Part A – Stephan Boltzman Law 1. Draw a graph of Irradiance versus Temperature on log-log paper. 2. Calculate the slope of the graph in order to demonstrate the law. 3. What does the slope indicate? Part B – Lambert’s Distance Law 1. Draw a graph of Irradiance versus Distance on log-log paper. 2. Calculate the slope of the graph of importance to this law. 3. What does the slope indicate? Part C – Lambert’s Direct Law (Cosine Law) 1. Tabulate the values of background illuminance, measured illuminance, corrected illuminance (measured – background) and normalized illuminance (corrected / illuminance at φ = 0o) for every angle taken. 2. Draw a graph of Corrected Illuminance reading versus Angle.

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

21

Semester 2, 08/09

TABLES FOR DATA COLLECTION & CALCULATIONS

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

22

Semester 2, 08/09

Experiment 1 – Thermal and Electrical Conductivity of Metals Part A – Heat Capacity of the Calorimeter Mass of lower calorimeter at room temperature = _____________ Room temperature = ____________ Temperature of hot water before pouring = ____________ Mass of hot water = ________ Time (sec)

Temperature (oC)

Time (sec)

Temperature (oC)

Time (sec)

0

110

210

10

120

220

20

130

230

30

140

240

40

150

250

50

160

260

60

170

270

70

180

280

80

190

290

90

200

300

Temperature (oC)

100

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

23

Semester 2, 08/09

Part B – Ambient Heat Mass of cold water = ____________ Time (mins) 0

Temperature (oC)

∆Q

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

24

Semester 2, 08/09

Part C – Thermal Conductivity Mass of cold water = ____________ Length between two thermocouples = __________

Time (sec)

Water Temperature (oC)

∆Q

ΔT (oC)

λ

0 30 60 90 120 150 180 210 240 270 300 Average

Part D – Electrical Conductivity Copper Reading

Current (A)

Voltage (V)

Resistance (Ω)

1 2 3 4 5 6 Average

Aluminium Reading

Current (A)

Voltage (V)

Resistance (Ω)

1 2 3 4 5 6 Average

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

25

Semester 2, 08/09

Experiment 2 - Heat Pump Part A – Water-water Heat Pump Mass of water: 1. condenser = ____________ 2. vaporizer = _____________

Time (min)

Power (W)

Condenser P1

θ1

θci

Vaporiser θco

P2

θ2

θvi

θvo

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Average

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

26

Semester 2, 08/09

Part B – Air-water Heat Pump Time (min)

Natural Air Power (W)

θ1

Hot Blower θvo

Power (W)

θ1

Cold Blower θvo

Power (W)

θ1

θvo

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Average

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

27

Semester 2, 08/09

Experiment 4 – Heat Conduction Linear Conduction Power (W)

10

10

Specimen

25 mm diameter Brass

16 mm diameter Brass

10 25 mm diameter Stainless Steel

o

T1 ( C) T2 (oC) T3 (oC) T4 (oC) T5 (oC) T6 (oC) T7 (oC) T8 (oC) Radial Conduction Power (W) T1 (oC) T2 (oC) T3 (oC) T4 (oC) T5 (oC) T6 (oC)

10

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

28

Semester 2, 08/09

Experiment 4 – Free and Forced Convection Flat Plate Heater Insert Fan speed Tin (oC) Tout (oC) T2 (oC) T3 (oC) T4 (oC) T5 (oC)

0

8

0

8

0

8

Fin Heater Insert Fan speed Tin (oC) Tout (oC) T2 (oC) T3 (oC) T4 (oC) T5 (oC) Cylinder Heater Insert Fan speed Tin (oC) Tout (oC) T2 (oC) T3 (oC) T4 (oC) T5 (oC)

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

29

Semester 2, 08/09

Experiment 5 – Thermal Radiation Part A - Stefan-Boltzmann Law Temperature

Radiometer Reading

Part B – Lambert’s Distance Law Distance

Radiometer Reading

Part C – Lambert’s Direct Law (Cosine Law) Angle

Background Illuminance (Lux)

Measured Illuminance (Lux)

Corrected Illuminance (Lux)

Normalised Illuminance (Unit 1)

0 10 20 30 40 50 60 70 80 90

Aerospace Engineering Lab 1 (MEC 2700) Thermal Science

30