Statement:
Selection of compressor and refrigerant for HVAC system that is operating on Vapor Compression Refrigeration System. The heat load is 120,000 BTU/hr and temperature is to be maintained at space is 50C.
Step 1:
Select ambient and environmental conditions
Step 2:
Select refrigerant, preliminary calculations, use of property charts, suction discharge pressure of compressor to achieve required cooling, compressor capacity etc.
Step 3:
Select compressor (Stage, rpm, displacement, size etc)

need detailed solution

Water is flowing in a compressor steadily at 20 kPa and 40 oC to 1.7 MPa and 500 oC. The power input to the compressor is determined to be 5 MW. The water enters the compressor at a height of 5 m and leaves at 10 m of height. The velocities of the water coming in and out of the compressor are 50 m/s and 180 m/s respectively. a) Determine the work input per unit mass for the water flowing through the compressor. b) Calculate required mass of flow rate of the water.

Find the change of entropy of a 2kg steam initially at 1MPa, 200C in a rigid tank until heated to 300C.

ANSWER THE FOLLOWING

1. What is a machine guide?

2. Why is a machine guide required in the manufacturing industry?

3. Provide 5 examples of machine guide, either by drawing or actual photos

4. When building a machine guide, what are the things to be considered? Why?

5. What difficulties did you encounter in making the shop exercise?

6. What is a fitment? Describe its importance in the manufacturing industry

7. What are tolerances? Why is it important?

8. Provide a flowchart diagram of how tolerances are analyzed and implemented.

9. What are tolerances?

10. To buy, a back saw what specification is needed?

11. When buying a claw hammer what specification is needed?

12. Give (2) functions of machine guide?

A steam power plant operates on an ideal regenerative Rankine cycle. Steam enters the turbine at 6 MPa and 450oC and is condensed in the condenser at 20 kPa. Steam is extracted from the turbine at 0.4 MPa to heat the feedwater in an open feedwater heater. Water leaves the feedwater heater as a saturated liquid. Show the cycle on a T-s diagram and determine the fraction of steam extracted from the turbine for the open feedwater heater.

How applied mechanics terminologies such as moment, moment of inertia and frictional matters are involved to theoretically design hydro power and wind mills for renewable energy supply?

Show the core design parameter’s hydro power and wind mills.  Related to them (terminologies in their usual applications) to perspective of Hydro-power and wind mills for theoretical design perfections

1. A turbojet engine is fitted to an aircraft flying at M = 0.65 in conditions where the

ambient temperature is 216 K and the ambient pressure is 18.75 kPa. You are to assume

adiabatic flow.

The following data on the engine are known:

Intake efficiency ?? = 1.00 Intake maximum pressure ratio ?? ??? = 0.95 Compressor pressure ratio ?? = 12 Compressor polytropic efficiency ?? = 1 Combustion chamber efficiency ?? = 1 Turbine Inlet temperature ?4 = 1796 ? Calculate:

a. The total temperature and pressure at entry to the compressor.

b. The total temperature and pressure at entry to the combustion chamber.

c. The fuel-to-air ratio in the combustion chamber.

1. Describe in detail the concept of primary and secondary tools in ergonomics. Provide example to demonstrate your understanding.

1. Propose and justify a workstation redesign to minimize the exposure you’ve selected. Provide pictures or sketching to assist your example.

Explain the advantages of a sodium-filled exhaust valve

An actual aircraft is cruising at -55.4°C, 18.8 kPa and 900 km/h. A heating system keeps the wings just above freezing temperatures of 0°C. Should the wing diameter evaluated as D = 0.5m, the following are to be determined:

(i) Estimate the suitable Nusselt number for this situation,

(ii) Compute the average convection heat transfer coefficient on the wing surface, and;

(iii) Evaluate the average rate of heat transfer per unit surface area.

Q3 (a) Describe the major independent and dependent variables that influencing cutting process

(b) A 150 mm long with 12.5 mm in diameter of a stainless steel rod is being reduced in diameter to 12.0 mm using a lathe machine. The machine spindle rotates at 400 rpm, and the tool is traveling at an axial speed of 200 mm/min. Determine;

(i) cutting speed

(ii) material removal rate, and

(iii) cutting time

(c) Briefly describe and differentiate between the melting process, pouring process and solidifying process in metal casting.

Ethics in Engineering

For each of the following five (5) scenarios, state briefly ‘what you would have done’ from an ethics perspective:

d) Dissent about quality

Discuss the ethical issue this case raises.

Dissent about quality

I

A recent graduate of Engineering Tech, Bernie Reston has been employed in the Research and Development (R&D) Chemical Engineering Division of Larom, Inc. for the past several months. Bernie was recommended to Larom as the top Engineering Tech graduate in chemical engineering.

Alex Smith, the head of Bernie's unit, showed immediate interest in Bernie's research on processes using a particular catalyst (call it B). However, until last week, his work assignments at Larom were in other areas.

A meeting of engineers in Bernie's unit is called by Alex. He announces that the unit must make a recommendation within the next two days on what catalyst should be used by Larom in processing a major product. It is clear to everyone that Alex is anticipating a brief, decisive meeting. One of the senior engineers volunteers, "We've been working on projects like this for years, and catalyst A seems to be the obvious choice." Several others immediately concur. Alex looks around the room and, hearing no further comments, says, "Well, it looks like we're in accord on this. Do we have consensus?"

So far Bernie has said nothing. He is not sure what further testing will show, but the testing he has been doing for the past week provides preliminary evidence that catalyst B may actually be best for this process. This is also in line with what his research at Engineering Tech suggested with somewhat similar processes. If catalyst B should turn out to be preferable, a great deal of money will be saved; and, in the long run, a fair amount of time will be saved as well. Should he mention his findings at this time, or should he simply defer to the senior engineers, who seem as determined as Alex to bring matters to closure?

II

Bernie somewhat hesitantly raises his hand. He briefly explains his test results and the advantages catalyst B might provide. Then he suggests that the unit might want to delay its recommendation for another two weeks so that he can conduct further tests.

Alex replies, "We don't have two weeks. We have two days." He then asks Bernie to write up the report, leaving out the preliminary data he has gathered about catalyst B. He says, "It would be nice to do some more testing, but we just don't have the time. Besides, I doubt if anything would show up in the next two weeks to change our minds. This is one of those times we have to be decisive--and we have to look decisive and quit beating around the bush. They're really getting impatient on this one. Anyway, we've had a lot of experience in this area."

Bernie replies that, even if the data on B is left out, the data on A is hardly conclusive. Alex replies, "Look you're a bright person. You can make the numbers look good without much difficulty--do the math backwards if you have to. Just get the report done in the next two days!"

Bernie likes working for Larom, and he feels lucky to have landed such a good job right out of Engineering Tech. He is also due for a significant pay raise soon if he plays his cards right.

What do you think Bernie should do? Explain your choice.

1. Write up the report as Alex says.
2. Refuse to write up the report, saying he will have no part in falsifying a report.
3. Other.

III

[Following II. 1.]

Bernie decides to write up the report. When he is finished, Alex asks him to sign it. Bernie now has second thoughts. He wonders if he should sign his name to a report that omits his preliminary research on catalyst B. Should he sign it?

IV

Bernie has now had more time to do research on catalyst B. After several weeks his research quite decisively indicates that, contrary to the expectations of Alex and the other more experienced engineers in the unit, catalyst B really would have been, far and away, the better choice. What should Bernie do now?

1. Keep the data to himself--don't make trouble.
2. Tell Alex and let him decide what, if anything, to do.
3. Other.

V

Bernie decides to say nothing. Although Larom has lost a lot of money by investing in an inferior catalyst, it is quite possible that this is the end of the matter for Bernie. The customer never complains, and no one outside at Larom raises any questions. However, it might go otherwise. Suppose a Larom competitor discovers that catalyst B is better for this type of work and it begins receiving contracts that Larom would normally be awarded. Further, what if Alex's superior then makes an inquiry into why his unit has missed out on this development?

VI

[Following II. 3.]

Bernie tries to convince Alex that a straightforward report should be submitted. Since there is a virtual consensus in the unit that catalyst A is best, A can be recommended. But the preliminary evidence about B can also be mentioned. After all, Bernie suggests, if the entire unit is convinced that A is best despite the preliminary evidence about B, why wouldn't those outside the unit be persuaded by the received wisdom of the unit? If they aren't persuaded, perhaps they will grant the unit more time to continue the research on B.

Somewhat to his surprise, Bernie finds Alex and the others receptive to his suggestion. The preliminary evidence about catalyst B is included in the report, even though A is recommended.

Unfortunately, Alex's superiors are very upset with the recommendation. They are unwilling to go ahead with the project without further testing, but they bitterly complain that the further delay will be very costly. Alex is severely criticised for not having a more convincing set of data. He, in turn, blames his staff, especially Bernie, the new specialist in this area. Bernie, Alex tells his superiors, failed to complete the necessary testing in a timely fashion. Alex tells his superiors that he should have supervised Bernie's work more closely, and he assures them that he will not let matters get out of control again. Although Bernie is not fired, he is not promoted and his salary is frozen for another year. What should he do?

1. Nothing. No good will come from complaining.
2. Confront Alex, telling him what you think of what he has done, but carrying it no further.
3. Other.

VII

Bernie decides he has nothing to gain from complaining to Alex or anyone else about becoming the "scapegoat" of the project. So, he keeps quiet. Sometime later, Alex is being considered for promotion to another division. Members of Bernie's unit are privately interviewed about his performance in the unit. Bernie is told that his comments will be kept confidential. What should he say in his interview?

VIII

Bernie says nothing negative about Alex in the interview. None of the others in the unit do either. Alex is promoted to another division. However, a year later it is discovered that he has directed someone in his new division to falsify data for reasons very similar to those in Bernie's original situation. The new person does what Alex asks. The result is a significant loss of money to Larom--only this time there is an expensive product-liability lawsuit relating to an unsafe Larom product. An inquiry takes place. The person who has falsified the report says that Alex has often requested that data be falsified--and that he typically has gotten young engineers to do the "dirty work" for him. So, it comes back to Bernie. He is asked why he didn't report Alex's orders to falsify data when the matter first came up. Bernie is accused of being partly responsible for allowing Alex to be promoted--with the resulting harm to others and loss of money and reputation to Larom.