Calculations for an Advanced Thermodynamics project: Refrigeration and Freezer Design
the project is Half done I need MORE calculations. I attached what I already have and those are the instructions:
You have a new job in a consulting company which has been hired to design a walk-in freezer and refrigerator for a new food transit warehouse. Your predecessor at the company calculated that the freezer needs a 10 ton cooling capacity while the refrigerator needs 30 tons of cooling. After completing these calculations, he quit (Uh-oh) so your job is to compete the design and to write a report that your boss can present to the builders in fulfillment of the contract.
It has been determined that the system will us Refrigerant 134a and that the freezer must be maintained between -10 and +5°F (-24 to -15°C) while the refrigerator must be kept between 37 and 45°F (3 to 7°C). Ambient conditions are expected to be as high as 100°F (38°C). Assume that refrigeration compressor efficiencies are 75%. Heat exchangers must maintain a 20°F (11°C) difference between the hot and cold sides at all locations.
It is customary to use a separate vapor-compression refrigeration cycle for each of the warehouse sections, but the boss says that other options should be explored and compared, because the owners are interested in saving money on expenses. This includes both first cost and operating expenses. The largest operating expense is typically the electricity to run the compressors, so reducing compressor work input and increasing coefficient of performance is important here. In general compressor work is reduced by having more that one compression stage and cooling the gas between stages. One such configuration is to put a flash chamber at an intermediate pressure between the compressors. See Problem 10.024 in the homework. First cost is related to many things including how many compressor systems are needed. There are several ways to have both refrigeration and freezer systems using only one compressor. See Problem 10.027 and Reserve Problem 10.003. (Both have been included in the WileyPlus homework labeled Problem 10.024 and solutions are visible to the student.)
In particular, you should find the power consumed in each scenario along with sufficient calculations and results to show which have the least consumption and the maximum coefficients of performance and also that each of them satisfies all of the constraints. You may use on-line tables for the refrigerant, but you need to be clear about the source of the data. You may work in either US or SI units as long as you find power consumption in kilowatts. You may assume that compressor inlets are at saturated vapor and that condenser outlets are saturated liquid.
Also assume that the steam is generated by burning natural gas (methane) and that the products of combustion must be maintained at or above the maximum steam temperature to calculate the energy available.
There are many aspects which go into this design. Your report must show that you have done enough calculations to convince me that you understand all of the aspects that need to be considered. This means showing trials that did not work and what changes you made to approach a solution that does work. Simply presenting a result is not sufficient. The thought process which goes into creating a design is of critical importance here.
NOTE: This is an open-ended project. There is no correct answer, just looking for sufficient detail in the calculations that an engineer can be reasonably certain that (1) the calculations and approaches are correct, (2) there are enough results that trends can be discerned, and (3) you have sufficient discussion that the reader can be confident that your conclusions are reasonable.