Atmospheric air enters the heated section of a circular tube at a flow rate of .005 kg/s and a temperature of 20 degrees Celsius. The tube is of diameter D = 50 mm, and fully developed conditions with h = 25 W/m^2K exist over the entire length of L = 3m.

a) For the case of the uniform surface heat flux at q''_s = 1000 W/m² , determine the total heat transfer rate q and the mean temperature of the air leaving the tube T_m,o. What is the value of the surface temperature at the tube inlet T_s,i and the outlet T_s,o? Sketch the axial variation of T_s and T_m. On the same figure, also sketch (qualitatively) the axial variation of T_s and T_m for the more realistic case in which the local convection coefficient varies with x.

b) If the surface heat flux varies linearly with x, such that q''_s(W/m²) = 500x(m), what are the values of q, T_m,o, T_s,i, and T_s,o? Sketch the axial variation of T_s and T_m. On the same figure, also sketch (qualitatively) the axial variation of T_s and T_m for the more realistic case in which the local convection coefficient varies with x.

c) For the two heating conditions of parts (a) and (b), plot the mean fluid and surface temperatures, T_m(x) and T_s(x), respectively, as functions of distance along the tuble. What effect will a fourfold increase in the convection coefficient have on the temperature distributions?

d) For each type of heating process, what heat fluxes are required to achieve an air outlet temperature of 125 degrees Celsius? Plot the temperature distributions.

List 4 issues that need to be considered when selecting a factor of safety in an

engineering design.

2-

What is the difference between yield strength and ultimate tensile strength of a material?

1. Figure 21.4 provides suggested cutting speeds and feeds for turn- ing. You are cutting a wrought carbon steel (1012) at normalized to 100 Bhn and have have selected a high speed steel tool. For a DOC of 150 in., What speed and feed would you select?

2. For problem 1, suppose you selected a speed of 145 sfpm and a feed of 0.015 in. per revolution. The workpiece is 4 in. in diameter.

a. What is the input rpm? b. What is the MRR? c. What is the cutting time for a 6-in. cut?

Only question 2 please.. if you need more info please let me know

The acceleration of certain objects is studied in an experimental test track for automobiles. The distance traveled by an object L is measured as a function of time t to yield the following:
t (s) 0.1 0.2 0.5 1.0 1.5 1.8 2.0 3.0

L (m) 0.26 0.55 1.56 3.90 7.41 10.28 12.6 30.

Obtain a best fit to this data, considering first-, second, and third-order polynomials. Using these polynomials, calculate the values of the dependent variable L at the time intervals employed for the given data to evaluate the accuracy of the polynomial representations. Discuss the results obtained.

Referring to the manual manufacturing method information given in reviewquestion 12, calculate the total annual cost to produce 100,000 parts per year. Note that theannual cost of maintenance for the machine is $16,000. Additionally, the raw material costis $2.50 per part.

1.

a)Which of the seven basic chip formation processes are single point and which are multiple point?

b)Why is metal cutting shear strain such an important parameter?

c)Why does the cutting force Fc increase with increased Feed or DOC?

d) The cutting conditions in a turning operation are: v = 2.1 m/s, f = 3.5 mm/revolution, and d = 0.24mm. The tool rake angle = 5 which produces a deformed chip thickness tc = 0.5 mm. Determine: (a) shear plane angle, (b) shear strain, and (c) material removal rate. Use the orthogonal cutting model as an approximation of the turning process.

The diffusion coefficients for carbon in nickel are given at two temperatures are as follows:

At T= 600°C, D=5.5 × 10^–14 m²/s

At T= 700°C, D=3.9 × 10^–13 m²/s

(a) Determine the values of D₀ and Q_d.

(b) What is the magnitude of D at 850°C?

A 10 ft long double pipe heat exchanger consisting of a 1 in sch 40 (1.315 in OD, 1.029 in ID) inner pipe within a 4 in sch 40 (3.998 in ID) outer pipe uses chilled water to cool hot glycerin (the water flows in the annulus and glycerin in the inner pipe). The pipes are constructed of AISI 302 stainless steel. The mean velocities of the water and glycerin are 4 ft/s and 1.3 ft/s, respectively. If the average bulk temperatures of the water and glycerin are 45 ◦F and 180 ◦F, respectively, compute the overall heat transfer coefficient based on the outer area of the 1 in diameter pipe. Neglect fouling.

Discuss the different types of pool boiling phenomena.

Describe the different behavior regions associated with pool-boiling in terms of excess temperature.

Describe the differences, if any, between burn-out point and Leidenfrost point for pool boiling.

For pool boiling, which thermo-physical variable needs to be controlled to obtain a continuous curve in the heat flux vs. excess temperature plot?

Discuss at which point does nucleate boiling regime starts and ends.

Describe the reason(s) for lower heat transfer coefficients relative to natural convection when excess temperature exceeds the burn-out point in a heat vs. excess temperature plot.

Discuss the reason(s) why quality is relevant during operation of power plant low pressure turbines.

How are Nerf N-Strike Elite Dart's made? What manufacturing process is done?  

A) What are cryogenic materials? Show how ductile to brittle transition zone takes place.
Determine its applicability.
B) Distinguish between thermosetting and thermoplastics polymers.
C) Discuss the nitriding process.

The following questions are simply applications of Bernoulli’s principle. (Give complete sentences as Answers.)

Why is the draft in a fireplace better on a windy day?

What keeps a Frisbee in flight?

Why does your car lurch toward an oncoming truck as it passes by?

Why does the wind increase the size of water waves?

Why do waves form as water approaches the shore?

Explain flow separation and why it causes increase or decrease in drag

A 1.5-in-diameter bar has been machined from an AISI 1050 cold-drawn bar. This part is to withstand a fluctuating tensile load varying from 0 to 62 kip. Because of the ends, and the fillet radius, a fatigue stress-concentration factor Kf is 1.85 for 106 or larger life. Estimate the fatigue factor of safety based on achieving infinite life (use Modified Goodman criteria) and the yielding factor of safety. If infinite life is not predicted, estimate the number of cycles to failure (use Modified Goodman criteria).

Write an executive summary on Ernst-Merchant Chip Formation theory and its practical applications in machining industries. (Hints: draw the free-body diagram and the force circle at the cutting edge, label all important parameters, explain the theory based on the minimum cutting force; show its importance on energy consumption and economy in mass production. (2 pages, single space, single column); use an abstract, divide the paper in headings and subheadings, and a conclusion or final remarks (summing up).