Mechanical Engineering Answers

17. The moisture removed from a material is 200 lb/hr and change of humidity ratio in dryer is 0.015. Determine the fan capacity if specific volume of air entering is 38 ft3/lb. Please explain the answer.

5. Two shafts 30 in. apart, each carrying a four-step pulley, are to be connected by a cross belt. The driving shaft is to turn 180 rpm while the driven shaft is to turn 50, 150, 250, and 600 rpm. The smallest step of the driver is 10 in. in diameter. Find (a) the diameters of all the steps, (b) angle of contact for each pair of pulleys, and (c) belt length.

4. A pulley 600 mm. in diameter transmits 40 kW at 500 rpm. The arc of contact between the belt and pulley is 144° having a center distance of 1100 mm. Determine: (a) diameter of the driven pulley for open belt drive, (b) speed of the driven pulley, and (c) belt length for open belt connection.

3. Two pulley 12 in diameter and 20 in diameter is connected by a crossed belt with center distance of 45 in. Find the belt length needed to connect them.

2. Two pulleys 10 in. diameter and 25 in. diameter is connected by an open belt with center distance of 40 in. Find the belt length needed to connect them.

1. A lathe having a 5-step pulley is driven by a belt, assumed to be crossed, from a pulley of the same size on the countershaft. The countershaft is to have a constant speed, and the lathe is to have speeds of 60 rpm and 135 rpm when the belt is on the steps either side of the center step. If the minimum speed is 40 rpm and the smallest diameter is 4 in., find the proper speed of the countershaft, maximum speed of the lathe, and the diameter of all steps on the pulleys.

How much product at 10% wet basis moisture would you obtain from drying 3.5 kg of carot (89% moisture)?

In a piston-cylinder arrangement of an engine there are 0.1 kg of gases at 4 MPa and 1527 °C at the beginning of the expansion stroke. The gases expand in a polytropic process with n =1.5 to a volume 10 times larger. Find the expansion work and the heat transfer. Assume the gas to be perfect gas with R= 0.287 kJ/kg-K, and Cv= 0.717 kJ/kg-K.

Two large parallel planes having emissivities of 0.4 and 0.6 are maintained at temperatures of 846 K and 288 K, respectively. A radiation shield having an emissivity of 0.2 on both sides is placed between the two planes. Calculate (a) the heat-transfer rate per unit area if the shield were not present, (b) the heat-transfer rate per unit area with the shield present. If the emissivity of the shield is increased by 50%, how many shields are needed for the heat transfer rate per unit area as compared with the obtained results from (b)?

6. A throttling calorimeter is connected to the superheated steam line supplying steam to the auxiliary feed pump on a ship. The line pressure measures 2.5 Mpa. The calorimeter pressure is 110 kpa and 150oC. Determine the entropy of the steam line. Please explain the answer.

Answer: a. 6.8 KJ/kg-oK c. 6.6 KJ/kg-oK

b. 6.2 KJ/kg-oK d. 7.5KJ/kg-oK