A closed loop ideal Brayton cycle is being designed to operate on water vapor. It is hypothesized that since water vapor has a high heat capacity and density the cycle eciency will improve over air. The maximum temperature for the cycle is limited to 1000C while a pressure ratio of 10 has been selected. The inlet of the compressor (state 1) will need to be 50C to reject heat to the surroundings at 30C. The pressure at state 1 is 125kPa to prevent surrounding air from entering the system in the event of a leak. Unfortunately, water would like to be a liquid at these conditions, and Brayton cycles do not like liquids. To deal with this it is proposed that the water vapor can be mixed with another gas to form a gas-vapor mixture where the water will not reach the dew point in the cycle.

1. What gas can carry the most water vapor at the state 1 conditions (i.e. has the highest ratio of water vapor mass to carrier gas mass)?
2. Regardless of your answer to the previous question, helium has been selected as the carrier gas for water vapor. Can this mixture be treated as an ideal gas everywhere in the cycle? (calculate the compressibility factor at each state to answer)
3. Ignoring the compressibility factors, treat the mixture as an ideal gas. What is the thermal eciency of the cycle?
4. What would the eciency be using pure helium? 

Please provide detailed answer, thanks

Homework Assignment 7

Due in Week 8 and worth 30 points

Theexperiment data in below table was to evaluate the effects of three variables on invoice errors for a company. Invoice errors had been a major contributor to lengthening the time that customers took to pay their invoices and increasing the accounts receivables for a major chemical company. It was conjectured that the errors might be due to the size of the customer (larger customers have more complex orders), the customer location (foreign orders are more complicated), and the type of product. A subset of the data is summarized in the following Table. 

Table: Invoice Experiment Error

Customer Size

Customer Location

Product Type

Number of Errors

–

–

–

15

+

–

–

18

–

+

–

6

+

+

–

2

–

–

+

19

+

–

+

23

–

+

+

16

+

+

+

21

Customer Size: Small (-), Large (+)

Customer Location: Foreign (-), Domestic (+)

Product Type: Commodity (-), Specialty (=)

Reference: Moen, Nolan, and Provost (R. D. Moen, T. W. Nolan and L. P. Provost. Improving Quality through Planned Experimentation. New York: McGraw-Hill, 1991)

Use the date in table above and answer the following questions in the space provided below:

1.    What is the nature of the effects of the factors studied in this experiment? 

2.    What strategy would you use to reduce invoice errors, given the results of this experiment?