Air (Cp = 1.005 kJ/kg · K) is to be preheated by hot exhaust gases in a cross-flow heat exchanger before it enters the furnace. Air enters the heat exchanger at 95 kPa and 20◦C at a rate of 0.90 kg/s. The combustion gases (Cp = 1.1 kJ/kg · K) enter at a rate of 1.1 kg/s and 150◦C. The product of the overall heat transfer coefficient and the heat transfer surface area is U A = 1200 W/K. Assuming both fluids to be unmixed, use the effectiveness-NTU method to determine

(a) the heat exchanger effectiveness,

(b) the rate of heat transfer, and

(c) the exit temperature of the exhaust gases.

• Write the Conservation of mass equation as it applies TO YOUR SYSTEM

• Write the Conservation of Energy equation as it applies TO YOUR SYSTEM

• List all the assumptions and idealizations for the process

1 cylinder, four-stroke, water-cooled, air injection of fuel
Output: 14.7 kW (20 hp)
Fuel consumption: 317 g/kWh (238 g/hp-hr)
Efficiency: 26.2%
Number of revolutions: 172 min^-1
Displacement volume: 19.6 L
Bore: 250 mm
Stroke: 400 mm

Q2/ Superheated steam enters convergent divergent nozzles at (2 MN/m²) and ( 325 C°) with mass flow rate (7.5 kg/sec ). It is expand according to (PV 13= C) through the nozzles until exit, while the exit pressure (0.36 MN/m³) Calculate 1/throat and exit diameter. 2/temperature degree of undercooling at exit.

PROJECT

4 : DESIGN A HYDRAULIC MOBILE CRANE

REQUIREMENTS:

•Design the system to carry load of up to 5000 lb

•Use a hydraulic winch(rotary actuator)to move the pulleys up and down

•Use fail-safe measures to support positive loads and run-away issues

•The speed of the crane shouldbe changeable

•Use dampeners to prevent vibration and maintain pressure and flow where necessar

What is the difference between dual duct and multizone air-conditioning systems? Which one provides more temperature variation across the zones and which one is economical to operate?

It is required to maintain the air in a building at 20oC and 40% saturation when the
outside conditions are 28oC, 50% saturation with a barometric pressure of 1.01325
bar. The total heat gains to the room (sensible plus latent) are 15 kW, and the latent
heat gains are 3 kW. There is no reciculation and the fresh air passes over a cooling
coil to dehumidify it, and then a heater, before entering the room. The cooling coil by
pass factor is 0.2; the volume flow of fresh air is 5 m3/s, calculate:
a. The temperature of the air leaving the cooling coil;
b. The refrigeration load for the coil;
c. The heat supplied in the heater
d. If the air-con system is to be adapted for use in winter with the same room
conditions of 20oC and 40% saturation. The mass flow rate of dry air from
the heater is to be kept the same as in summer. The outside conditions are
-5oC, 100% saturation, and the sensible heat loss from the conditioned
space is 34.5 kW with the same latent heat gain of 3 kW. A saving in
energy is obtained by recirculating a portion of the room air using a mixing
box and dispensing with the washer. Calculate
i. The ratio of room air to fresh air that must be used for the system to
operate satisfactory;
ii. The heat supplied in the heater under these conditions.

Q1 : A cascade refrigeration system is designed to supply 10 tonnes of refrigeration at an evaporator temperature of -40°C and a condenser temperature of 36°C. The load at -40°C is absorbed by a unit using R-22 as the refrigerant and is rejected to a cascade condenser at -10°C. The cascade condenser is cooled by a unit using R-12 as the refrigerant and operating between - 20°C evaporating temperature and 36°C condenser temperature. The refrigerant leaving the R-22 condenser is subcooled by 5°C but there is no subcooling of R-12 refrigerant. The gas leaving both the evaporators is dry and saturated and the compressions are isentropic. Neglecting losses. the enthalpy of refrigerant at lower evaporator exit is : * A--154.89 [kJ/kg] B-334.18 [kJ/kg] C-388.13 [kJ/kg] D-163.86 [kJ/kg] -----------------------------------------------Q2 : A cascade refrigeration system is designed to supply 10 tonnes of refrigeration at an evaporator temperature of -40°C and a condenser temperature of 36°C. The load at -40°C is absorbed by a unit using R-22 as the refrigerant and is rejected to a cascade condenser at -10°C. The cascade condenser is cooled by a unit using R-12 as the refrigerant and operating between - 20°C evaporating temperature and 36°C condenser temperature. The refrigerant leaving the R-22 condenser is subcooled by 6°C but there is no subcooling of R-12 refrigerant. The gas leaving both the evaporators is dry and saturated and the compressions are isentropic. Neglecting losses. calculate the COP of whole system

a) There are different ways of categorizing the wide variety of available
joining processes. According to classification by the American Welding
Society (AWS), joining processes fall into three major categories i.e
welding, adhesive bonding and mechanical fastening. Compare these
three various joining methods in term of its strength and easy to
manufacture characteristics.

b) Some types of welding processes can be classified into both fusion and
solid-state categories. Distinguish the fundamental process for both
categories.

c) Shielded metal-arc welding (SMAW) is one of the oldest, simplest, and
most versatile joining processes. About 50% of construction,
shipbuilding, pipelines, and maintenance work industrial currently
performed by this process. Illustrate and use a schematic diagram to show
the equipment and the shielded metal-arc welding process.

Q3) Three methods of supplying a 100 000 MJ workload and a 300 000 MJ heat load to a new shopping mall are to be compared. Work in the form of electricity is available from the National grid at 5c per MJ and heat in the form of hydr-carbon fuel is available at a cost of 2 cper MJ

The three methods are,

1. Electricity purchased for both Heat load and work load,
2. Using a 25% efficient fuel burning heat engine to supply work and a fuel fired furnace to supply the heat load.
3. Using a 20% efficient fuel burning heat engine.to supply the work load and using heat rejected by the heat engine to supply the heat load.

Determine the most economical method of supplying the requirements of the Mall.      

what can you say about newtons law of viscosity and pascals law ???

?? / ? = (?? - ?) ?? / ?
Since it is;
a) By mathematical analysis, show which Mach number the critical section will be.
b) In which nozzle does the critical section occur? Why? Explain by drawing a figure.
c) Which diffuser creates critical section? Why? Drawing a shape please explain.

this is a energy system homework of energy systems lecture from mechanical engineering thank you for efforts

QI: Choose the appropriate answer A, B, C, or D (25 point) 1- In the open loop transfer function, what is the relationship between input and output signals? (A) Output does not depend on the input (C) Input depends on the Output 2-The suitable test signal for the system that is subjected to shock inputs is ------. (A) Ramp function (B) Step function (C) Impulse function (D) None of above 3-The error signal is equal to the difference between (A) Desired and feedback (B)Output and feedback (C)Desired and disturbance (D)None of (B) Input does not depend on the Output (D) none of above signals. above 4- If a sensor can measure the position of an object on power-up relative to a reference (the distance of the object from a reference point on power-up), it is called- (A) Incremental sensor (B) Absolute sensor (C) Velocity sensor (D) None of above 5- The key to ---- operating principle is that the change in the position of the rotor element changes the electromagnetic coupling (magnetic flux linkage) between the two windings. (A) syncro sensors (C) linear variable differential transformer (LVDT) sensor (D) temperature sensor (B) pressure sensor

A solid cylindrical shaft, 3 in. dia. 20 in. long, is used for the transmission of mechanical power at a rate of 50 hp running at 1300 rpm. The modulus of rigidity for the material used is 16 × 10⁶ psi. Calculate:

1. the shear stress acting on the shaft;
2. the torsional deflection of the shaft.

design and perform your experimentation and evaluate the energy storage performance of these sensible heat thermal energy storage system natural number friction factor are to be found using friction and Reynolds number and what fraction attempt and develop more functional relationship for natural number and fractional factorial using first order