Shows a new process in which 0.0100 kg of methane (an ideal gas) is compressed from a pressure of 0.100 MPa and a temperature of 20.0 °C to a pressure of 10.0 MPa in a polytropic process with n = 1.35. Determine the moving boundary work required.

Determine the work required in Example 4.5 if the final pressure of the methane is 0.500 MPa.

If the work required in Example 4.5 is ?5.00 kJ, determine the final temperature and pressure of the methane.

If the gas used in Example 4.5 were air, determine the work required to compress it polytropically from 14.7 psia, 70.0°F to 150.°F with n = 1.33.

A counterflow, concentric tube heat exchanger used for engine cooling has been in service for an extended period of time. The heat transfer surface area of the exchanger is 5 m², and the design value of the overall convection coefficient (without any fouling) is 38 W/m²K. During a test run, engine oil flowing at 0.1 kg/s is cooled from 110^oC to 66^oC by water supplied at a temperature of 25^oC and a flow rate of 0.18 kg/s. Determine whether fouling has occurred during the service period. If so, calculate the fouling factor, R^”_f (m²K/W). Specific heat of engine oil is 2166 J/kgK, and water is 4178 J/kgK.

What is R^”_f = x 10^-3 m²K/W?

Design a concentric tube heat exchanger (in co-current configuration) to heat 1000 cm3/ min of water from 30oC to 45oC flowing in the shell, using water at 65oC flowing in the tube. The heating water should not exit with temperature above 55oC. Choose a suitable range of inner pipe (copper material) diameters for heat exchanger, assume suitable inner tube thickness and outer tube diameter and show selection of parameters and dimensions for an optimum design.

Prob. 4-68 A piston–cylinder device contains 2.2 kg of nitrogen initially at 100 kPa and 25C. The nitrogen is now compressed slowly in a polytropic process during which PV^1.3 = constant until the volume is reduced by one-half. Determine the work done and the heat transfer for this process.

4–69    Reconsider Prob. 4–68. Using EES (or other) software,plot the process described in the problem on a P-V diagram, and investigate the effect of the poly- tropic exponent n on the boundary work and heat transfer. Let the polytropic exponent vary from 1.0 to 1.4. Plot the boundary work and the heat transfer versus the polytropic exponent, and discuss the results.

A cylinder contains ethylene, C2H4, at 1.536 MPa, -13oC. It is now compressed in a reversible isobaric (constant pressure) process to saturated liquid. Find the specific work, heat transfer and entropy generated.

A strip of elastomer 1 cm×1 cm×10 cm is stretched to 25 cm length at T =25C, a stress of 1.5 MPa being required

(a) Assuming a tetrafunctional crosslinking mode, how many moles of network chains are there per cubic centimeter?

(b) What stress is required to stretch the sample to only 15 cm at T = 25C?

(c) What stress is required to stretch the sample to 25 cm length at 100C?

The theory of rubber elasticity and the theory of ideal gas dynamics show that the two equations, G = nRT and PV = n'RT, share certain common thermodynamic ideas.

What are they?

a) Define the following terms:

i) Calorific Value

ii) Volumetric Percentage with respect to air composition

iii) Gravimetric percentage with respect to air composition

iv) Stoichiometric Ratio

b) In combustion chemistry, state why the usage of excess oxygen is often desirable.

c) Consider the combustion of pentane. Determine:

i) The stoichiometric air to fuel ratio

ii) The excess air supplied, if 8% CO2 (by vol) is found in the dry product. ( Take air to be 21% Oxygen,and 79% Nitrogen)

. A disposable coffee cup (including a lid) may be regarded as a polystyrene cylinder, diameter 50mm, height 80mm and thickness 2.5mm. The base and lid may be regarded as 2.5mm thick disks. When being held using finger tips (having a very small area) the heat transfer coefficient from the outside of the cup is 20W/m2K and from the coffee to the inner wall is 100W/m2K. Estimate the rate of heat loss from the cup when the coffee is at 65oC and ambient temperature is 18oC. The conductivity of the polystyrene is 0.04W/mK.

Ans = 6.33W

An ideal four stroke Otto cycle engine has 6 cylinders and a displacement of 4 Liters. It has a compression ratio of 8.5:1. If the mean effective pressure is 4000 kPa when operating at 3000 rpm, what will be the indicated power and what is the required heat transfer to the engine from a combusting fuel?

A ½” diameter UNC, SAE Grade 8, bolt with rolled threads is preloaded to 70% of its proof strength when clamping a 2.75” thick sandwich of solid steel. Find the safety factors against static yielding, fatigue failure and joint separation when am external fatigue load having Fmax=1000 lbf and R=0 load is applied.