Refrigerant 134a enters a horizontal pipe operating at steady state at 40°C, 300 kPa, and a velocity of 25 m/s. At the exit, the temperature is 70°C and the pressure is 240 kPa. The pipe diameter is 0.01 m. Determine: (a) the mass flow rate of the refrigerant, in kg/s, (b) the velocity at the exit, in m/s, and (c) the rate of heat transfer between the pipe and its surroundings, in kW.

Problem 4.016 SI Refrigerant 134a enters a horizontal pipe operating at steady state at 40°C, 300 kPa, and a velocity of 25 m/s. At the exit, the temperature is 90°C and the pressure is 240 kPa. The pipe diameter is 0.1 m. Determine: (a) the mass flow rate of the refrigerant, in kg/s, (b) the velocity at the exit, in m/s, and (c) the rate of heat transfer between the pipe and its surroundings, in kW.

A pipe fitted with a closed valve connects two tanks. One tank contains a 5kg mixture of 62.5 percent CO2 and 37.5 percent O2 on a mole basis at 30C and 125kpa. The second tank contains 10kg of N2 at 15C and 200kPa. The valve in the pipe is opened and the gases are allowed to mix. During the mixing process 100kJ of heat enrgy is supplied to the combined tanks. Determine the final pressure and temperature of the mixture and the total volume of the mixture.

Explain the significance of Charles Lindbergh's epic flight to the growth of aviation.

Calculate the fatigue stress concentration for a steel filleted shaft that is loaded axially.

Given Data:

Sut = 690 MPa

D (for larger cross-section) = 54 mm

d (for smaller cross-section) = 40 mm

r(fillet radius) = 3 mm

A vertical composite rod made up from a solid part connected in series with a hollow part
is fixed at its top end and has a collar attached at the lower end.
The following data is average

 solid rod length 320 mm;
 solid rod diameter 50 mm;
 hollow rod length 280 mm;
 hollow rod diameters 50 mm and 28 mm;

Draw a neat sketch of the arrangement and for an applied load of 1,5 kN calculate:

4.1 the maximum stress and resilience of the compound rod, when the weight
is applied suddenly without impact; (7)

4.2 the maximum stress in the compound rod, when the weight is allowed
to fall freely through a height h = 20 mm (7)
Assume E = 200 GPa.

The flowing formulae may be used:
1 2
2 2
;
2
;
2
AL U U U
E
U
E
L
AL w h
E
    





 
  

Water at a mean temperature of 80 °C and a mean velocity of 0.15 m/s flows inside a 2.5 cm ID and 3.3 cm OD, copper tube. Atmospheric air at 20 °C and a velocity of 10 m/s flows across the tube. Calculate the overall heat transfer coefficient based on the outer surface and the rate of heat loss per 1 m length of the tube for inside and outside fouling factor 0.00018 m2. What is the percent reduction in the overall heat transfer coefficient due to the dirty conditions in the heat exchanger? (Assume that the value the waterside heat transfer coefficient is 250 W/m2.°C and that of the airside is 75 W/m2.°C.

A 50-tooth spur gear is in mesh with a 27-tooth pinion. The gears have a diametral pitch of 5 teeth/in, and a pressure angle of φ = 25°. The gears transmit 80 HP at 4000 pinion rpm.

Find the factors of safety against bending and surface failure. Assume that the teeth are full depth, Qv = 10, a through hardened to 360 HB steel gear, and a carburized and case hardened steel pinion. Assume a face width of 3.0 in, a 99.9% reliability, and a life of 9 5 10 × cycles.

A pair of helical gears is used with the following properties: 14.5 degree normal pressure angle, 45 degree helix angle, diametral pitch of 8 teeth/in, 1.5-in face width, and normal diametral pitch of 11.31 teeth/in. The pinion has 12 teeth and a 1.5in pitch diameter, and the gear has 32 teeth and a 4.0 in pitch diameter. Both gears have full-depth teeth. If a right-hand pinion and a left hand gear are placed in mesh, find the transverse contact ratio, the normal contact ratio, the axial contact ratio, and the total contact ratio.

An AISI 1010 carbon steel plate of 1 by 1 m size and of 6 mm thickness is hung vertically after a heat treatment to 300°C uniform temperature. It is cooled by ambient air at 20°C flowing parallel to the plate in transverse direction.

a) Considering both forced and natural convection, for 8 m/s transverse air velocity, determine the rate of heat transfer from the plate and the corresponding instantaneous rate of change of the plate temperature.

b) For the transverse air velocities in 1-15 m/s range, plot the heat transfer coefficients from the plate associated with forced convection, natural convection and mixed convection on the same graph.

5 t/hr of soybean oil is pumped through a smooth stainless steel pipe 5 cm in diameter at 30C.

A) What will the coefficient of friction be?

B) If by heating the oil its viscosity can be reduced by a factor of 5 and its density by 5%, how will the fraction be affected?

C) Suppose the pipe is not smooth as originally thought. how would the assumed fraction be affected?

D) If the pumping distance were extended by 50% and the pipe's diameter changed to 7 cm, how will the pressure drop (as a result of friction) be affected?

A transformer that is 10 cm long, 6.2 cm wide, and 5 cm high is to be cooled by attaching a 10 cm x 6.2 cm wide gold heat sink to its top surface. The heat sink has seven fins, which are 5 mm high, 2 mm thick, and 10 cm long. A fan blows air at 25°C with a velocity of 6 m/s parallel to the passages between the fins. The heat sink is to dissipate 12 W of heat and the base temperature of the heat sink is not to exceed 45 °C to maintain safe operation. Is this design enough to cool the transformer to safe levels?

 I have to write a review paper of one measurement technique (any device you feel interested in or have experience with), which could be what I have learned in Mechanical Measurement course.
The main content should include how it operates, its application, changes in design with time, and future direction. Although I have to focus on recent and future development.

Would you give me any examples of devices or suggest essay topics ?