Theory Quiz

Note: The Expected Completion Time for this quiz is 60 mins but, the Maximum Available Time to complete the quiz is 90 mins.

Total Number of Questions - 45

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Heat Transfer for Structures - Theory Quiz

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1 / 45

When napthalene balls are placed inside a cupboard, after a few months their size reduces. Which phase change is responsible for this?

2 / 45

The equation for surface to surface radiative heat flow rate is given as $Q_{ij}=A_{i}\varepsilon_{i}F_{ij}\sigma(T_{i}^{4}-T_{j}^{4})$ where $A_{i}$ is the area of surface i, $\varepsilon_{i}$ is the emissivity of surface i, $F_{ij}$ is the view factor from surface i to surface j, $\sigma$ is the Stefan-Boltzmann constant, and $T_{i}$ and $T_{j}$ are the surfaces temperatures.
Using unit analysis, what are the SI units of Q?

3 / 45

Heat flows from a _____. Select 2 best answers.

4 / 45

When ice is placed in a glass, tiny droplets of water form on the outer surface of the glass. This is an example of:

5 / 45

To increase the radiative heat transfer between bodies, which of the following will be most effective. Pick the three best options.

6 / 45

The Fourier's law becomes nonlinear when _____.

7 / 45

How is specific heat defined?

8 / 45

Why does food cook faster in a pressure cooker?

9 / 45

Heat transfer by convection occurs _____. Select the best option.

10 / 45

Which of the following factors affect a material's emissivity? Select the three best options

11 / 45

The fan in the laptop is cooling the electronic components by _____.

12 / 45

When simulating a transient thermal analysis with the objective of finding temperature distribution over the body at different times, which of the following are required to be defined? Select the three best options.

13 / 45

Heat transfer through thermal contact primarily occurs through _____. Select the best answer.

14 / 45

Which of the following properties are desirable when choosing a liquid coolant? Select the two best options.

15 / 45

The expression for the rate of the heat flow (Q) by conduction through the single pane window is _____, where $K$ is the thermal conductivity of the glass; $l$ is the thickness of the glass, $A$ is window surface area; $T_1$ is the temperature on the outside surface of the window, $T_2$ is the temperature on the inside surface of the window, and $T_2>T_1$

16 / 45

What is the equation of the heat transfer?

17 / 45

What is thermal conductivity? Select the 2 best answers.

18 / 45

An important parameter while choosing a material for cookware is that it needs to heat up quickly and uniformly so that the food inside gets cooked faster. Assuming that this is the sole criterion, which of the following metals do you think is best suited to be made into a cookware?

19 / 45

For a given amount of the heat flux, if the thermal conductivity becomes larger, then the thermal gradient becomes _____.

20 / 45

21 / 45

The equation $\sum_{j=1}^{n}F_{ij}=1$ basically states that:

22 / 45

Why is the heat sink designed with so many fins?

23 / 45

Film coefficient may be dependent upon which physical variables? Choose 3 best options.

24 / 45

In a tubular heat exchanger, two separated fluids exchange heat, such as one fluid flowing around a pipe and another fluid flowing inside the same pipe. Let's assume that the convective film coefficients of two fluids are $h_{1} = 120 W/m^{2}K$ and $h_{2} = 12000 W/m^{2}K$ respectively. What is the most effective way to improve the overall heat transfer efficiency?

25 / 45

Which material has the lowest thermal conductivity?

26 / 45

Let surface 1 be a spherical surface with area of $1m^{2}$. It is placed inside surface 2 which is a fully enclosed box with area of $2 m^{2}$. We can expect the view factor $F_{21}$ to be:

27 / 45

An arbitrary surface 1 of area $A_{1}$ is inside a perfect enclosed arbitrary surface 2 of area $A_{2}$. If the view factor $F_{12}$ is given, how can the view factor $F_{22}$ be determined?

28 / 45

3D printing constructs three-dimensional objects by depositing material layer-by-layer. It is an industrial application of which of the following phase changes?

29 / 45

Choose an example which best illustrates convective heat transfer.

30 / 45

Radiative heat transfer requires _____ for heat transfer between the bodies to occur.

31 / 45

In a steady-state thermal analyis, the calculated temperature distribution depends on which of the following factors? Select the three best options.

32 / 45

Which of following statements is correct if an object takes 10 minutes to cool down from 100 °C to 80 °C, then how much time will it take if it has to cool down from 80 °C to 60 °C? Assume that the external conditions remain constant and the bulk temperature is at 20 °C.

33 / 45

Two plates of equal size are radiating heat to each other. There are three "vectors" to consider in this situation - the surface normals of each plate and a line connecting the centers of both plates. If we just consider changing the orientation of the plates, keeping the plates at a given distance apart, select the best option that maximizes the radiative heat transfer between the plates.

34 / 45

Thermal conductivityy of most non-metals _____.

35 / 45

The surface to surface radiative heat transfer between two surfaces depends on which of the following:

36 / 45

What is the driving force for natural convection? Choose the best option from the following.

37 / 45

The method commonly used in finite element analysis to solve a nonlinear problem is called _____.

38 / 45

With respect to radiative heat transfer, which is a true statement?

39 / 45

In terms of heat capacitance, which of the following fluids is best suited to be used as a coolant? Assume that the coolant is a stationary pool of liquid, so that heat capacitance is the major factor contributing to its ability to absorb heat from the target surface to be cooled.

40 / 45

A warm object is placed in a cool room in order to decrease its temperature. Which of the following actions would the improve heat transfer rate?

41 / 45

Which two processes are involved in Convective Heat Transfer?

42 / 45

Heat transfer by convection requires _____.

43 / 45

The temperature in the Fourier's law is analogus to the _____ in the Ohm's law.

44 / 45

If surface roughness is increased, how will film coefficient be affected? Select the best option.

45 / 45

A toaster oven heats up the bread predominantly via _____.