CASE STUDY

In the Appliances Manufacturing Plant, a large number of engineering activities are carried out in a wide range of areas. These activities include design, production of parts, assembly, testing, and quality assurance.

Many of the manufacturing processes in the plant are performed using automated technologies and equipment. People also perform some of the manufacturing tasks and the plant employs over 400 workers. The decision on whether people or machines will be used for a particular task is dependent on many factors, including costs, time, quality and worker health and safety.

The plant considered here produces a many part for appliances and assembles them. Among the parts produced are door and housing materials and parts, compressors, motors, fans, some exterior parts, and electronics components. The plant normally operates three shifts per day and has production lines including machining equipment, conveyers and overhead cranes, punch presses, and paint-spray booths. The plant utilizes electricity and natural gas extensively.

A number of workers at the plant have over the last six months been subject to several different health problems. The following information has been received by the head engineer at the plant.

The head engineer at the plant wants to ensure that the plant provides a safe and healthy environment. So, she decides to ask an engineering health and safety consulting company to do a health and safety audit of the plant. The report provided by the consulting company lists the following safety problems:

a)     An expert on fires and explosions notes that the extensive use of natural gas in the plant could lead to an explosion in the plant in some circumstances. The force of such an explosion could lead to severe injuries or deaths of workers and, possibly, cause the building to be damaged or to collapse. The potential for an explosion could develop if a sufficient natural gas leak occurs or the plant ventilation system fails to perform properly or certain controls or sensors fail. But, the expert further notes, there is insufficient

         information available on the concentration of natural gas in the plant air, as only one natural gas sensor is in place at the plant, but it is not located in the main area where an accumulation of natural gas is likely to occur. Thus, the potential for an explosion could exist, yet not be detected or acted upon. In addition, the expert is concerned because the natural gas sensor is connected neither to an automated shut-off system for the natural gas supply nor to an alarm, thus increasing the likelihood of an incident and its potential severity.

b)     Although maintenance is supposed to be done quarterly on the natural gas lines and equipment, no evidence is found that maintenance has ever been performed since they were first installed four years ago. Such maintenance typically involves checking for and fixing gas leaks. Also, no training has been provided to workers on either understanding the potential for explosion, or the steps to take to avoid an explosion. In fact, most workers did not even realize the potential for an explosion existed. Furthermore, no written procedures relating explosions exist within the plant.

c)      The plant contains toxic materials that can harm people and animals. The way this material is stored in the plant, it could, in the event of a plant explosion, be released and impact an area within one kilometer of the plant. Such an incident could lead to illnesses or deaths among members of the public and could harm animals in the environment.

Questions:

1)     If the head engineer at the plant decides that measures must be taken to protect health and

         safety, but the plant manager refuses to approve the measures, what are the obligations of

         the head engineer?

2)      Do any of the problems cited demonstrate that it is best to address health and safety

         comprehensively in the early stages of an engineering activity, preferably within the

         design process and not as an afterthought? For instance, can you indicate some measures

         that will likely be more expensive to implement to fix the problem compared to the cost

         that would have been incurred during the design process to resolve the problem then?

CASE STUDY

In the Appliances Manufacturing Plant, a large number of engineering activities are carried out in a wide range of areas. These activities include design, production of parts, assembly, testing, and quality assurance.

Many of the manufacturing processes in the plant are performed using automated technologies and equipment. People also perform some of the manufacturing tasks and the plant employs over 400 workers. The decision on whether people or machines will be used for a particular task is dependent on many factors, including costs, time, quality and worker health and safety.

The plant considered here produces a many part for appliances and assembles them. Among the parts produced are door and housing materials and parts, compressors, motors, fans, some exterior parts, and electronics components. The plant normally operates three shifts per day and has production lines including machining equipment, conveyers and overhead cranes, punch presses, and paint-spray booths. The plant utilizes electricity and natural gas extensively.

A number of workers at the plant have over the last six months been subject to several different health problems. The following information has been received by the head engineer at the plant.

The head engineer at the plant wants to ensure that the plant provides a safe and healthy environment. So, she decides to ask an engineering health and safety consulting company to do a health and safety audit of the plant. The report provided by the consulting company lists the following safety problems:

a)     An expert on fires and explosions notes that the extensive use of natural gas in the plant could lead to an explosion in the plant in some circumstances. The force of such an explosion could lead to severe injuries or deaths of workers and, possibly, cause the building to be damaged or to collapse. The potential for an explosion could develop if a sufficient natural gas leak occurs or the plant ventilation system fails to perform properly or certain controls or sensors fail. But, the expert further notes, there is insufficient

         information available on the concentration of natural gas in the plant air, as only one natural gas sensor is in place at the plant, but it is not located in the main area where an accumulation of natural gas is likely to occur. Thus, the potential for an explosion could exist, yet not be detected or acted upon. In addition, the expert is concerned because the natural gas sensor is connected neither to an automated shut-off system for the natural gas supply nor to an alarm, thus increasing the likelihood of an incident and its potential severity.

b)     Although maintenance is supposed to be done quarterly on the natural gas lines and equipment, no evidence is found that maintenance has ever been performed since they were first installed four years ago. Such maintenance typically involves checking for and fixing gas leaks. Also, no training has been provided to workers on either understanding the potential for explosion, or the steps to take to avoid an explosion. In fact, most workers did not even realize the potential for an explosion existed. Furthermore, no written procedures relating explosions exist within the plant.

c)      The plant contains toxic materials that can harm people and animals. The way this material is stored in the plant, it could, in the event of a plant explosion, be released and impact an area within one kilometer of the plant. Such an incident could lead to illnesses or deaths among members of the public and could harm animals in the environment.

Questions:

1)     What are the unsafe conditions and acts in the plant?

2)     What are some steps can be taken to rectify the noted safety concerns?

A water-to-water system is used to test the effects of changing tube length, baffle spacing, tube pitch, pitch layout, and tube diameter. Cold water at 25°C and 100,000 kg/hr is heated by hot water at 100°C , also at 100,000 kg/hr. The exchanger has a 31 in. ID shell. Perform calculations on this 1–2 shell-and-tube heat exchanger for the following conditions, as outlined in the examples, and put together an overall comparison chart. a. 3/4 in. OD tubes, 12 BWG laid out on a 1 in. triangular pitch; 3 baffles per meter of tube length. Analyze the exchanger for tube lengths of 2, 3, 4, and 5 m. b. 3/4 in. OD tubes, 12 BWG laid out on a 1 in. triangular pitch; 2 m long. Analyze for baffle placement of 1 baffle per meter of tube length, 2 baffles per meter of tube length, 3 baffles per meter of tube length, 4 baffles per meter of tube length, and 5 baffles per meter of tube length. c. 3/4 in. OD tubes, 12 BWG; 2 m long; 4 baffles per meter of tube length. Analyze the exchanger for tube layouts of 15/16 in. triangular pitch, 1 in. triangular pitch, and 1 in. square pitch. d. 1 m OD tubes, 12 BWG; 4 m long; 9 baffles. Analyze the exchanger for tube layouts of 1.25 in. triangular pitch and 1.25 in. square pitch. e. 3/4 in. OD tubes, 12 BWG laid out on a 1 in. triangular pitch; 2 m long; 4 baffles per meter of tube length. Analyze the exchanger for 2, 4, 6, and 8 tube passes, and compare to the case of true counterflow (i.e., 1 tube pass).

This is problem 5-17 from El-Wakil’s Powerplant Technology book -- consider a simple combination turbine with one Delaval impulse stage and one 60 percent reaction stage. The nozzle of impulse stage receives steam at 900 psia and 900°F and leaves it at 300 psia. The nozzle efficiency is 97 percent and its angle is 20°. The blade speed is optimum and its velocity coefficient is 0.95. The impulse stage is followed on the same shaft by the reaction stage which exhausts to 100 psia. The steam entrance angles for that stage are also 20°. The efficiency of the fixed blades (nozzles) is 90 percent. Because of different diameters of the impulse and reaction moving blades, the velocity of the reaction blade is 1.5 that of the impulse blade. (a) Determine all steam velocities and draw the velocity diagram of the combined turbine, (b) calculate the work of each stage, in Btus per pound mass, and (c) calculate the individual stage and the turbine efficiencies.

Prove that any planar F-dof (degree of freedom) linkage (contains lower pairs only) must have at least F+3 binary links.

This is problem 5-13 from El-Wakil’s Powerplant Technology book -- a 50 percent reaction stage in a steam turbine undergoes a total of 20 Btu/lb_m enthalpy drop. The nozzle efficiency and angle are 88 percent and 25°, respectively. The blades move at 420 ft/s and have V_r1 = 332 ft/s, V_s2 = 386 ft/s, and ? = 22°. The steam flow is 1.08x10⁶ lb_m/h. Find (a) the work done by the stage in horsepower and megawatts, (b) the blade efficiency, (c) the stage (nozzle and blade) efficiency, and (d) the blade velocity corresponding to maximum efficiency, in feet per second.

5. A power cycle receives energy QH by heat transfer from a high temperature energy source at TH = 2000 K and rejects energy QL by heat transfer to a low temperature energy sink at TL = 400 K. For each of the following cases determine whether the cycle operate reversibly, irreversibly, or is impossible.

(a) QH = 1200 kJ, Wcycle = 1020 kJ.

(b) QH = 1200 kJ, QL = 240 kJ.

(c) Wcycle = 1400 kJ, QL = 600 kJ.

(d) efficiency = 40%.

Air at 1 atm and 27 degree C flows across a flat plate at a velocity of 14 m/s. Find the distance from the leading edge where transition to turbulent flow begins and the local heat-transfer coefficient at this point if the temperature of the plate is 77 degree C.

A piston?cylinder device initially contains 1.5?kg saturated liquid water at 120°C. Now heat is transferred to the water until the volume increases 100 times.

Determine:

a. Initial Volume of the water.

b. Final volume of water.

c. Final state of water.

d. Amount of heat added to the water

e. Draw the T?s diagram

What are the largest and smallest turbulent length scales in an unstratified open drain of depth 1 m that is flowing at velocity U=10 cm s^-1 ? Assume q=0.1U. Is the flow turbulent?

Discussion: Design Feasibility Studies and Alternatives in testbed

-Load can break bearing: dynamic and static load

- bearing life expectancy of bearing

- how the measurment of part and equiqment help you to determine force and whight ?

Aircraft Structural Engineering "consider you are designing the aircraft, how you will specify the bulkhead distances in aircraft fuselage?" i want the procedure of the calculations for this. OR give me some proper stuff to study about it, any book (with page numbers), or any link.

Plot schematic stress strain diagram for composite material. Show each stage in the graph and explain them.

Illustrate how ferromagnetic and paramagnetic material behaves under external field and after removal of external field.

Derive Green’s Theorem from Sturm-Liouville Eigen Value problem. When do you need Green’s theorem in the context of a Heat or Diffusion Equation?