Refrigerant 134a enters an insulated compressor operating at steady state as saturated vapor at -20^oC with a volumetric flow rate of 0.18 m³/s. Refrigerant exits at 9 bar, 70^oC. Changes in kinetic and potential energy from inlet to exit can be ignored.

Determine the volumetric flow rate at the exit, in m³/s, and the compressor power, in kW.

The following design and operating data were taken for a large industrial centrifugal water pump:

Required water flow rate varies from 500 m3/h to 700 m3/h. For the pump to deliver 550 m3/h, the flowrate has been reduced by partially closing the delivery valve. Motor efficiency is 93%.

a. Calculate the pump operating efficiency (the ratio of pumping power to operating pump input power delivered TO THE MOTOR.

b. Pump operating efficiency is low because of the partial valve closing to control the flowrate. What would be the best way to improve pump operating efficiency?

c. The ratio of two pump volumetric flowrates would be equal to the ratio of two pump shaft speeds to what power? The ratio of two pump operating heads would be equal to the ratio of two pump shaft speeds to what power? The ratio of two pump operating powers would be equal to the ratio of two pump shaft speeds to what power?

d. Suppose the pump energy improvement idea suggested in part b. was used for the pump. From the relations in part c., calculate the pump speed required to give a volumetric flowrate 550 m3/h. That is, (550 m3/h / design flowrate) = (RPM to deliver 550 m3/h / design RPM). From this, calculate the pumping power needed to deliver 550 m3/h using the design pumping power ratio. The difference in the operating values of the pumping power (124 kW and the pumping power with the new energy efficiency feature) is the energy savings.

Machine X costs $248,751 and has annual operating and maintenance costs of $9,980. Machine Y costs $264,500 and has annual operating and maintenance cost of $5,120. Both machines are Class 39, which specifies a CCA rate of 25%. The company needs the machines for 11 years, and at the end of year 11 machine X can be sold for $12,257 and machine Y can be sold for 13,033. The Company's MARR is 10%, and its marginal tax rate is 35%. Do an after-tax analysis to determine which machine should be chosen.

There is a vapor compression type refrigeration cycle using the refrigerant HFC 134 a. In the condenser, it is isostatically cooled, the condensation temperature is 50 ° C., and the condenser outlet is the compressed liquid at 45 ° C. In the evaporator, it is isothermally heated, the evaporation temperature is 10 ° C. and the outlet of the evaporator is heated steam at 15 ° C. When the expansion valve performs isenthalpic expansion, and the adiabatic efficiency of the compressor is 0.70, answer the following questions.

(a) Calculate the specific enthalpy of the compressor outlet temperature, specific enthalpy, condenser outlet and evaporator outlet.
(b) Obtain the cooling operation coefficient of this system.
(c) Obtain the circulation amount of the refrigerant necessary for obtaining the cooling effect of 3.0 kW in this system.

Answer:
(a) Compressor outlet: 68 ° C, 445 [kJ / kg], condenser outlet: 264 [kJ / kg]
Evaporator outlet: 409 [kJ / kg] (b) 4.03 (c) 0.021 [kg / s]

Consider a double wedge airfoil with a maximum thickness of 5% chord at angle of attack = 0 degrees.

a. Determine the approximate chord wise location (x/c) of the maximum thickness that producesthe minimum drag coefficient (cd) at Mach numbers of 2, 4 and 6. [Hint: you do not need to investigate locations ahead of 0.4c]. Include a composite plot of drag coefficient vs location of (t/c) max for each Mach number in your report.

b. Repeat this analysis for an airfoil with 10% maximum thickness. Include the calculated values on your composite plot of part I.a.

c. Discuss what your results say about the effects of Mach number and thickness on minimum drag coefficient.

Write a brief note about the type of fits and tolerances in machine elements subject under mechanical engineering

Part 1. Select an object from your everyday life that GD&T could be applied to. Attach a graphic image of it (a photograph, a scanned sketch or a computer generated drawing) in JPEG format here.

Part 2. Identify two primary functions of this part (e.g. must assemble to other part(s), smooth rolling, must not wobble when placed on a flat surface). Briefly describe the functions (maximum of 200 words).

Part 3. Assign a minimum of two geometric tolerances (including at least one that requires the use of datums) to the part to ensure that the part will successfully achieve its two primary functions. Assign datums as necessary. Create a sketch or drawing to show where the datums and tolerances will be applied. Assign values for the tolerances, however you will not be marked on the magnitude of the tolerances.

Part 4. Briefly describe (maximum of 150 words) how the part would be inspected to verify that it meets the geometric tolerances.

Q4. Explain the concept of kinematic coefficients? Why do we need to “square” and “cube” the angular velocities, in order to obtain time derivatives using the second order and third order kinematic coefficients, respectively?

The velocity profile for a steady laminar flow in a circular pipe of radius R given be u=u0( 1- r^2/R^2). if the fluid density varies with radial distance r from the centerline as p=p0 ( 1+ r/R)^1/4 where p0 is the fluid density at the pipe center, obtain a relation for the bulk fluid density in the tube.

A request has been received from an external customer for recommendations for linear position control sensors to be used in an explosive environment. For this reason unsafe electrical contacts must be avoided. The sensors will be installed in locations that are hazardous to access except when the plant is shut down annually for maintenance. The span required is 5 cm. The sensor case must not permit any ingress of dust or of water.

State what type of position sensors you would recommend and give your reasons. Sketch both the recommended sensor and circuit, and explain its operation. Comment on how signal conditioning requirements can now be met. Identify the durability required in respect of dust and water ingress.

If you are using a double braid rope that has a breaking strength of 8,600 pounds, how much can safety be liftedonce a knot is tied in the rope?

a. 860

b. 2,000

c. 1,500

d. 650

1) From the data table given, compute the population standard deviation, ?.
2) From the data table given, compute the Upper Control Limit for s (UCLs)
3) From the data table given, compute the centerline, Xbar-bar.
4) From the data table given, compute the Average of s values, sbar.
5)Calculate the Upper Control Limit, UCLXbar
6) From the data table given, compute the Lower Control Limit, LCLXbar

This table was all the information given. I was wondering if I was missing some information. Are any of these questions answerable with just the information given?

List five methods you can enhance heat transfer in a duct

A student conducts an experiment boiling water in a 3.96L pot. The Diameter of the base of the pot is 7-3/4” and the height is 5-1/8”.

2 Liters of water @ 23°C takes 17 minutes before it reaches a boil. It has a height in the pot of 2-3/4”. The process took 1 hour and 13 minutes to boil dry. How much energy was required to do this?

#1 A mass measurement system behaves as a second-order system (consisting of a mass = 50g, a spring, and a viscous damping element). To determine the damping the ratio, the system was exposed to a step input and decaying oscillating amplitude of the system output was measured. Results of these measurements showed that the damping ratio = 0.7 and the ringing frequency f_d =389 Hz. Calculate the following and report results using 3 significant digits minimum:

The natural frequency, in Hz

The spring constant, in kN/m

Logarithmic decrement ln(x₁/x_n)

The period of oscillation when the system is exposed to a step input, in milliseconds

The dynamic error, ?, at 450 Hz in % (include the sign of the error)

The phase and time delay between input and output for sinusoidal inputs of 450 Hz in rad and milliseconds, respectively

Can we use this system to measure mass in outer space? How? Use a diagram to explain.