Engineering Answers

A Diesel cycle has a compression ratio of 16. The lowest and highest temperature of the

cycle are 300K and 1880K respectively. The pressure at the beginning of compression is 1 Bar.

Calculate:

a) The pressure and temperatures at all the other points of the cycle.

b) Net work output.

c) Efficiency of the cycle.

An open cylindrical tank 4 ft in diameter and 6 ft deep is filled with water and rotated about it's axis at 60 rpm. How much liquid is spilled, and how deep is the water at the axis?

1.Aside from area by triangles, what are other common methods used in determining/ measuring the required area?

2. What are the similarities and/or differences of each method?

A standard cast from pipe inner diameter = 50mm and outer diameter is insulated with 85% magnesium insulation (k = 0.02w/mc) temperature at interface between the pipe and insulation is 300 degree celcius, the allowable heat loss through pipe is 600w/m length of pipe

In order to reduce cooling electricity consumption in an industrial plant, it is proposed to install an absorption refrigeration system running on solar energy. The absorption system costs $300,000 and the operating and maintenance expenses are $8000 per year. It is estimated that this absorption system will save $27,500 per year from the electricity they save. The lifetime of the system is expected to be 20 years with an average annual inflation-adjusted interest rate of 4 percent. The system will have no salvage value after 20 years of its lifetime. Would you support this project from an economic point of view? How would you evaluate this project if the inflation-adjusted interest rate is 2 percent?

Springbok (South Africa) City or Windhoek (Namibia) are considered for the installation of a solar power plant utilizing parabolic trough collectors. The total area of the collectors is 6000 m2 and the average efficiency of the plant is estimated to be 15 percent. Using the average daily solar radiation values on a horizontal surface available online, determine the amount of electricity that can be produced in each city.

Compare the amount of solar energy input to a horizontal surface for winter and summer months in Cairo (Egypt) and Upington (South Africa). Determine the ratio of solar energy input in summer to that in winter for each city.

As a consulting engineer, you are tasked to advise on an installation of solar panels for the purpose of supplying a household that contains 1 double-door fridge, 1 x 150 L deep freezer, 1 x 65” TV, 1 x desktop computer (with 2 screens), 1 x combo internet rooter-modem and 1 water-pump used to supply a water tank (2 occupants). The above appliances should be able to operate off-grid. Please advise on what it would cost and payback period (Desired storage autonomy 36 hrs).

The absorber surface of a solar collector is made of aluminum coated with black nickel oxide (α1 = 0.92 and ε = 0.08). The collector is to be installed in Stellenbosch (South Africa). The air and the effective sky temperatures are 20 and 7°C, respectively, and the convection heat transfer coefficient is 15 W/m2·K. For an absorber surface temperature of 60°C, determine the net rate of solar energy delivered by the absorber plate to the water circulating behind it.

The beam shown is under the action of a uniformly distributed load w of 3kN/m between the supports and a point load of 2k/N at the end point. Determine the bending moment in kNm at point A situated 4 m to the right of the left support Round off your answer to one decimal place and use the standard sign convection for the bending moment