Consider a Carnot-cycle heat pump with R-410a as the working fluid. Heat is rejected from the R410a at 35 oC, during which process the R-410a changes from saturated vapor to saturated liquid. The heat is transferred to the R-410a at 0 oC. The specific volume during the isothermal heat addition process at 0 oC changes from 0.00841 m3 /kg to 0.02994 m3 /kg.
a. Show the cycle on P-T, P-v, and T-v diagrams.
b. Find the quality at the beginning and at the end of the isothermal heat addition process at 0 oC.
c. Find the pressure and specific volume at the four points.
d. Find the specific heat and specific work at each process.
e. Find the net specific heat and the net specific work during the cycle.
f. Determine the COP of the cycle using heat and work.
g. Determine the COP of the cycle using temperatures.
In: Mechanical Engineering
A system for the storage of thermal energy is to be designed using an underground tank of water. The tank is buried at a depth of 3 m and is a cube of 1 m on each side. The water in the tank is heated by circulating it through a solar energy collection system. A given heat input to the water may be assumed due to the solar energy flux. Characterize the design problem in terms of the fixed quantities and design variables. please solve and explain
In: Mechanical Engineering
1. Is the strength of a beam under a static load necessarily related its stiffness?
2. Distinguish between primary failure and secondary failure.
In: Mechanical Engineering
NOTE: What would the anwser be if it was a square plate with a circular hole?
The metallic, circular plate of diameter D and thickness t, has a concentric hole of diameter h in its middle, as shown. Metal density is ? = 8000 kg/m3 ; D = 5 cm.
1) When h = 0 (no hole), determine the maximum thickness t [in mm] so that the plate can stay afloat on the surface of water at 20°C.
2) The plate’s thickness is now 1 mm. Show that, in order for the plate to stay afloat on water surface, the hole’s diameter h satisfies a quadratic equation of the form h2 + Ah + B = 0, where A and B are constants. Using S.I. units [m, kg, s] and with h in m, determine the numerical values of A and B.
In: Mechanical Engineering
Water is contained in a closed, rigid, 0.2 m3 tank at an initial pressure of 5 bar and a quality of 50%. Heat transfer occurs until the tank contains only saturated vapor. Determine a)the final mass of vapor in the tank, in kg,b) the final pressure, in bar.
In: Mechanical Engineering
1. _____ lead to distortion surrounding the welded joints.
(a) Residual stresses (b) Cracks (c) Overlap (d) Incomplete fusion
2. Which of the following is NOT an issue in welded joints?
(a) Porosity (b) Cracks (c) Residual Stresses (d) Hot Shots
3. Which of the following is a solid state welding processes?
(a) Brazing (b) Soldering (c) Cold Welding (d) SMAW
4. In which of the following welding processes, filler metals only are melted at temperatures above 450°C?
(a) Brazing (b) Soldering (c) Cold Welding (d) SMAW
5. Which of the following is involved in friction welding process:
(a) Heat (b) Pressure (c) Both of them (d) None of them
6. In resistance welding, the required energy is generated by chemical reactions
(a) True (b) False
In: Mechanical Engineering
What is transient heat transfer? why it is important?
In: Mechanical Engineering
Please type the answer
Q) For the short to medium- term (10 to 50 years). State a minimum of five realistic steps (not subsidies) that can be implemented to achieve a sustainable energy solution for the world.
In: Mechanical Engineering
Please type the answer
Q) For the short to medium- term (10 to 50 years). State a minimum of five realistic steps (not subsidies) that can be implemented to achieve a sustainable energy solution for the world.
In: Mechanical Engineering
An interesting flow results from superposition of a point source with strength m located at the origin and a uniform flow of strength U. Find the complex potential for this flow combination and graph the streamlines. Then, find the stagnation points and find the streamfunction at the stagnation point.
In: Mechanical Engineering
A refrigerant (R-134 A) at 0.8 MPa and 30 deg Celcius is throttled in a steady flow to a lower pressure and a temperature of -10 deg Celcius. What is the specific entropy generated? You can make the usual assumptions that are made for a throttle.
In: Mechanical Engineering
An oil cooler is in the form of a single shell 4 tube heat exchanger in which oil passes through the tubes and cool water passes through the shell. Water comes in at 15C and leaves at 25C and has a mass flow rate of 20 kg/min. Oil enters at 35C with a mass flow rate of 30 kg/min. Cp of oil is 2.13 kJ/KgC and that of water is 4.18 kJ/kgC. If the surface area of the heat exchanger is 0.5 m2, calculate the overall heat transfer coefficient. Assume the heat exchanger is adiabatic with regards to the surroundings.
In: Mechanical Engineering
how can i redesign a simple bench vise inorder to decraese the total assembly time in solid works
In: Mechanical Engineering
The cantilever is affixed to the free end of a square cross-section piezoelectric (PZT) block, which is fixed at the other end. Draw the schematic of the lumped-parameter model of the cantilever-PZT system, obtain the mathematical model of this mechanical system, and derive the lumped mass and stiffness of the PZT knowing that la = 0.01 m (length of PZT block), a = 0.005 m (side length of PZT cross-section), EPZT = 55 GPa (Young’s modulus), ?PZT = 7500 kg/m3 (mass density). The piezoelectric material losses are represented by an equivalent viscous damping coefficient cPZT = 60 N-s/m.
In: Mechanical Engineering
Compare how Griffith determined critical crack length, ac, with how the value of r*is determined in the solidification process.
In: Mechanical Engineering