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  1. Right you are, sorry for not answering sooner . Thanks for letting me know. I think it might have been a typo on my part in the question. My question still stands though, do i multiply 1200 kg x 334? This gets me 400800 Kj/ per 24 hrs. If i divided by 24 I get 16700 Kj/hr or 278.33 Kj/min. Is this the correct answer? Thanks again.
  2. Help I'm hoping someone can help me out on this question. What is the capacity in tonnes of refrigeration of a system in which 1200 kg of the refrigerant are circulated per hour? The enthalpy of the vaporized refrigerant leaving the evaporator is 118 kj/kg and the enthalpy of the liquid refrigerant enetering the expansion valve is 64.66 kj/kg. I believe i have figured out the net refrigerating effect. It is done by subtracting the enthapy of liquid refrigerant enetering the expansion valve from enthapy of the vaporized refrigerant leaving the evaporator. That is 181 kj/kg-64.66 kj/kg = 116.34 kj/kg. The next step of the equation i'm not sure about. I know that the heat of fusion which is the amount of heat required to melt 1 kg of a substance, of ice is 334 kj. To melt 1000 kg of ice would require 334 x 1000= 334 000 kj. Therefore 1 tonne of refrigeration = 334 000 kj per hour. So do i multiply 1200 kg x 334 kj??? I did that and got 400 800 kj/24 hour. Final conversion to minutes gets me 278 kj/min. Is this right? can anyone help with this? Does anyone of anywhere else i can go for help?
  3. Not sure if this is where this post should be but here goes. I need to calculate the minimum thickness required for a welded steel pipe of material SA 312 grade TP 347, plain end. The outside diameter of the pipe is 273.1 mm and the operating pressure and temperature are 2000 kPa and 400 degrees C respectively. I believe i need a table from the ASME Poer Boilers Code but the only thing i could find was a reference in Paragraph PG.-27.2.2 and no table.Anyone have any ideas? Thanks
  4. I need help with a question. A material to be used for a piston rod has an ultimate strength of 414 000 kPa. The maximum load on the piston is to be 70 000 N and the safety factor for the rod is 12. Calculate the working stress of the piston rod and the diameter of the piston rod? How do i begin. I know that Stress = load divided by area, but how do I find the area when i don't know the size of the material? What am i missing? That's all the information I have. Thx
  5. Any help on this one would be appreciated. A mass of 0.987 Kg of air at 101.3 kPa absolute and a temperature of 15 degrees C is compressed isothermally to a pressure of 500 kPa absolute and a volume of 0.0163 cubic meters. If R for air is 0.287 kJ/Kg K, what will be the work done?
  6. Thanks again Dave. The answer i came up with was 5492.19 squared cm. Is it possible for you to verify that.
  7. Thanks guys for your help, For some reason i can't wrap my brain around this one. Dave would you mind drawing a diagram. Thanks again muchly appreciated.
  8. The boiler shell is 5 meters long. Sorry for any cunfusion
  9. Can anyone help me with this one. A horizontal boiler shell is 150 cm in diameter and 5m long. It is filled with water to a depth of 100 cm. What is the area of the segment of the end plate above the water line? I'm not sure where to begin with this one. Do i have to find the Areas of the Circle, Sector and the triangle and then subtract the triangle area from the sector area to get the area of the segment? If so how do i find the triangle area, what numbers do i use? Am i even going in the right direction with this one? Thanks in advance
  10. Hey guys. Thanks for all the help in the past. I now have another question to solve. Not sure which equation to use or even how to start . Here's the question. Four kg of ice, are mixed with 60 kg of water which is at a temperature of 50 degrees C and the resultant temperature is 40 degree C. Calculate the initial temperature of the ice if its SPECIFIC heat is 2.04 kj/kg K and it LATENT heat is 335 kj/kg. Take the specific heat of water as 4.2 kj/kgK. Thanks again
  11. operator


    Thanks dave for the last piece of information. I find myself stuck on a question about triangles. What is the side length of an equilateral triangle if the area is 1732 cm squared. What is the equation? I'm missing something? Thanks in advance
  12. Help I;m not very good in math and I need to find the answers to this question. A steel tie bar 7 m long, 10 cm wide and 1.25 cm thick is subjected to a tensile force of 133 000 N. cALCULATE; A. The stress produced in the bar B. The strain produced C. The amount the bar is stretched in cm. How do i find the answer?
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