A Rankine cycle power plant is being developed to operate an irrigation system. In this power plant solar energy will be used to boil a low boiling point fluid within glazed flat plate solar collectors. The working fluid that has been selected is the commonly used refrigerant R 134a (1, 1, 1, 2 tetrafluoroethane), tabulated properties of which may be found in Tables A11, A12 and A13 at the rear of the prescribed text.

The plates being used for the solar collector are made of 2 layers of aluminium bonded together for much of their area and incorporating tubular passages of oval cross-section in the unbonded areas, within which the refrigerant boils. The working pressure of this construction is 1400 kPa. It is intended that the refrigerant will boil at this pressure and be slightly superheated, thereby bringing the temperature up to 55 C. The quality of the glazing and insulation on the solar collectors is such that at these fluid conditions, and with a solar intensity of 1 kW per square metre onto the glazing, the efficiency of solar energy collection into the fluid is 70%.

The superheated vapour is fed from the boiler to a small turbine, the isentropic efficiency of which is 85 % x (1.07). The turbine will drive an electric generator whose output will be used in part to provide power for the boiler feed pump whose isentropic efficiency is 96 % / (1.02). The remainder of the electricity will be used to drive an irrigation pump and charge up batteries for use in less sunny periods.

The irrigation pump is responsible for taking cold water from a stream, through the condenser of the power plant and on from that to drip irrigation trickle hoses in the fields nearby. The condenser and a water pump are positioned in a concrete lined pit below the stream level to ensure the pump is always primed and the condenser water tubes are free of air locks. The trickle hoses are laid out in the fields above the stream level. When the power plant is operating at the design condition of 1 kW per square metre solar intensity, the water flow rate through the condenser is to be such that it rises in temperature from 12 to 23 C. At this condition the saturation temperature of the refrigerant in the condenser will be 32 C. The refrigerant is to enter the boiler feed pump at the saturation temperature as a fully condensed liquid.

The various components of the power plant are to be sized such that the net electric output available for the water pump and battery charging is 1.8 kW when the rate of solar energy incidence on the collector glazing is 1 kW per square metre. The efficiency of the electric generator is 82% / (1.07) and the efficiency of the electric motor driving the boiler feed pump it is 75% x (1.02).

2. Considering the real case, where the turbine and feed pump are not isentropic, and the feed pump electric motor and the electric generator are not 100% efficient (assume no pressure drop in boiler and condenser):

a. Determine the specific enthalpy of the refrigerant at the entry and exit of the feed pump, and the entry and exit of the turbine;
b. Sketch and label the process paths of the cycle on a T-s diagram, an h-s diagram and a p-v diagram, also showing the saturated liquid and vapour lines on each diagram.
c. Determine, per kg/sec of refrigerant circulated
d. For the design requirement of 1.8 kW net electrical power output, determine, for the real case
i. the necessary mass flow rate of refrigerant;
ii. the electrical power input to the boiler feed pump motor
iii. the electric output power rating of the turbo generator
iv. the necessary solar collector area
v. the necessary water flow rate through the condenser

1. Use the passion curve handout to make an n = 200, c = 1 OC curve and answer the following questions.

   (4 pts)

   1. Use the OC curve to determine the percentage of lots that will be accepted when the true lot

      proportion defective is 1%, 2%, and 4%.

   2. What is the AQL?

   3. What is the RQL?

   4. What is the IQL?

An ideal Otto engine has a compression ratio of 10 and uses air as the working fluid. The state of air at the beginning of the compression process is 100 kPa and 27 ⁰C. The maximum temperature in the cycle is 2100K. (R=0.287 for air) (using variable specific heat)

1. Draw the P-v diagram of the Otto cycle
2. Determine the specific internal energies at the beginning and the end of the compression,
3. Determine the specific internal energies before and after the expansion
4. Determine the specific heat input, heat rejection and net-work output.
5. Determine the thermal efficiency.
6. If the amount of air in one cylinder at the beginning of compression is 500 cm³, how much power can the engine deliver for an 8 cylinder engine running at 2000rpm?

An air conditioning system is to take outdoor air at 30 ^oC and 70% relative humidity at a steady rate of 10 m³/s and to condition it to 25 ^oC and 50% relative humidity. The outdoor air is first cooled down to 13.9 ^oC using cooling coil and then heated to the desired condition in the heating section. Assuming the air is at 1 atm pressure,

1. Draw the air conditioning process on the attached psychometric chart.
2. Determine the mass flow rate of the dry air.
3. Determine the amount of the water condensed by the cooling coil.
4. Determine the amount of heat removed by the cooling coil.
5. Determine the rates of heat supplied in the heating section.

CASE 750W MICROWAVE OVEN. COMPULSORY In your new role as quality manager of the high-tech unit of a large national company, you identify a problem which is typified by the two internal memos shown below. MEMO 1 From: Marketing Manager To: Managing Director Cc: Production Director Works Manager Date: 4th January 2020 We have recently carried out a customer survey to examine how well we are doing in the market. Regarding our product range, the reactions were generally good, but the 750 W microwave oven is a problem. Without exception everyone we interviewed said that its quality is not good enough and could potentially be hazardous. Although it is not yet apparent, we will inevitably lose our market share to our rivals if we do not swiftly address this issue. Also, we will not want our customers to report these issues to the Ghana Standards Authority (GSA), as we are aware of the grave implications, given they have emphasized the possibility of bodily harm using our product. As a matter of urgency, therefore, will you please authorize a complete redesign of this product, and the possibility to recall the product category? MEMO 2 From: Works Manager To: Production Manager Cc: Managing Director Marketing Manager Date: 6th January 2020 This really is ridiculous! I have all the QC records for the past ten years on this product. How can there be anything seriously wrong with the quality when we only get 0.1 per cent rejects at final inspection and less than 0.01 per cent returns from customers? REQUIRED Using the case above, kindly answer the questions below. It is of utmost importance not to import any ideas or presumptions other than those expressly stated in the case. While you answer these questions, be conscious of the weight allocated to each question. Brevity is advised!

1. Discuss two (2) major quality “fitness” dimension(s) explored in the case? [5 Marks]

2. Assuming your firm is certified to use the 1SO 9001:2015 standard, indicate how the auditable clauses of in your organization’s Quality Manual can apply to your case study in a problem resolution endeavour. [14 Marks]

3. Use a process map hinged on the 4-stage process cycle (PDCA) to resolve the firm’s quality problem. [8 Marks]

4. Show how the firm should handle the nonconforming outputs according to ISO 9001:2015? [6 Marks]

A cylinder(σY= 230 MPa)which is initially free from residual stress has internal radius b = 20 mm and external radiusa= 50 mm. Determine:

a)The maximum internal pressure without yielding the cylinder. Give your answer in MPa.[5 marks]

b)The fully plastic internal pressure. Give your answer in MPa.[5 marks]c)The radius to which the material yields, when the pressure is 150 MPa. Give your answer in mm.[10 marks]

c)The cylinder is loaded by internal pressure, pi, which, when released, causes residual stress in the hoop direction of-0.5σYat the internal radius.

Determine:d)The internal pressure,pi.Give your answer in MPa.[25marks]

A refrigeration system with a flash chamber operates with R134a between the pressure limits of 1.0 and 0.1 MPa. The refrigerant leaves the condenser as saturated liquid and is throttled to a flash chamber operating at 0.4 MPa. The refrigerant leaving the low-pressure compressor at 0.4 MPa is also routed to the flash chamber. The vapor in the flash chamber is then compressed to the condenser pressure by the high-pressure compressor, and the liquid is throttled to the evaporator pressure. Assume the refrigerant leaves the evaporator as saturated vapor and compressors are isentropic. (The pressures are absolute pressures)

1. Draw P-h diagram for the refrigeration cycle on the attached P-h diagram.
2. The fraction of the refrigerant vapor enters the flash chamber after the first throttle valve.
3. The enthalpy of the refrigerant vapor at the flash chamber (where the two streams of vapor meet).
4. The amount of heat removed from the refrigerated space for a mass of 0.5 kg/s through condenser.
5. The power input to the compressors.
6. The coefficient of performance for the refrigeration system.

3.1. Oil with (ρ = 788 kg/m3 and ν=0.00067 m2 is removed to the atmosphere through a pipe, 7mm diameter, and 37m long. The pipe is located 3.5m from the top of the oil. If the pipe is build using smooth stainless steel, find the flow rate of the oil and the condition of the flow.

3.2. A water tank is located at the top of the roof with 20°C of water that will be used for showers. The tank is connected to a 25m long and 17mm diameter of asphalted cast iron pipe with 6 bends (KL = 1.2). Water needs to flow at 60 L/s, find the high of the water level. (Use Moody Chart for your reference)

Each axis of a two-axis plotter utilises a stepper motor with 60 pulses per revolution. For each axis, the output is coupled to a lead screw with a 13:1 gear reduction and has a pitch = 0.9mm. The table is required to travel along a linear trajectory with neither axis exceeding a travel speed of 160mm/min. To achieve an incremental position of 310mm along the x-axis and 800mm along the y-axis, determine the motor speed required for the y-axis in Hz.

The department has been approached by the school superintendent about starting a Fire and Life Safety Education Program for all grades, K-12. As the fire inspector, this project will fall under your responsibility. The superintendent has asked that you submit your program plan in writing so that it can be reviewed and discussed at the next school board meeting. If your plan is approved, the program will begin the next school year. However, there are budget constraints, and several members of the school board feel like there are more important areas and programs that need funding.

You are to create a plan for a Fire and Life Safety Education Program. Given the circumstances with some of the school board members, your plan should begin with a summary of a comprehensive overview of general fire safety for occupied buildings. You should also demonstrate rationale for the general fire safety provisions as methods of fire protection. Let them know how important this program is through the short-term and long-term benefits to students and to the community as a whole. Also, be sure to include the following:

• goals for the program,
• organization of grades (Will you group some grades?),
• a broad outline of the topics to be taught,
• broad details of any special events/activities, and
• a plan to keep the program going, year after year. (Will certain grades be taught certain topics each year so that, as student progress, they learn new things?)

Your response must be at least two pages in length, in APA style. All sources used, including the textbook, must be referenced; paraphrased and quoted material must have accompanying APA citations. The title and reference pages are not included in the page-count requirement.

In an interchangeable system, why is statistical approach is preferred over a complete interchangeability approach? State the condition for complete interchangeability approach.

1. An air conditioner using R134a as the working fluid operates on an ideal vapour compression system between 0.3 and 0.8 MPa. If the specified capacity for air conditioning is 20 kW. What would be its capacity for food freezing for which the evaporator temperature -20^oC. Show the cycle on a PH diagram and explain the effect of the changes to the compressor and condenser respectively.

1. A bio-reactor is kept at 45°C on a day where the outside is 20°C. It is estimated that the bio-reactor loses 12 kW to the ambient. Waste heat at 450 K from an engine is used to deliver the heat to the bio-reactor. Find the destruction of exergy and where it is made.
   
   
   
2. The condenser in a power plant cools 10 kg/s water at 10 kPa, quality 90%, so it comes out as saturated liquid at 10 kPa. The cooling is done by ocean water coming in at ambient 15°C and returned to the ocean at 20°C. Find the second-law efficiency of the condenser.