A mechanical aim rotates in the vertical plan about point O. The slider P (m = 2 kg) is drawn toward O with a constant speed (?̇) of 0.5 m/s through the rough slot (friction coefficient µ = 0.1) by pulling on the free end E of the cord. At the instant when r = 0.25 m, the arm is rotating with a constant speed (?̇) of 10 rad/s in the clockwise direction.


When the slider is oriented at an angle of θ = 30° from the horizontal:

a) Plot the free body diagram for P, using r-? coordiantes; show positive r and ? directions (4 points)

b) Determine the normal force between the slider and the slot, in N (7 points)

c) Determine the tension in the cord, in N (7 points)

d) Which side (A or B) is in contact with the slider? Why? (2 points)

The air inside inside a house is 14 ^oC and the convective heat transfer coefficient h = 11 W/m2⋅°C. The air outside the house is 49 ^oC and the convective heat transfer coefficient h = 7 W/m2⋅°C. A window has dimensions (2m x 2.5m x 8mm) and heat conduction of 0.8W/mk. Determine the total heat resistance through the window in ^oC/W

A CI engine operating on the air standard diesel cycle has cylinder condtioons at the start of compression of 65 degrees C and 130 kPa. light diesel fuel is used at an equivalence ratio of 0.8 with a combustion efficiency of 0.98. compression ratio = 18 Calculate:

1. temperature and pressure in each state of the cycle (0c)
2. pressure at each state of the cycle (kpa)
3. cutoff ratio
4. indicated thermal efficiency (%)
5. heat lost in exhaust (KJ/Kg)

A converging-diverging nozzle is designed to operate with an exit Mach
number of 2. The nozzle is supplied from an air reservoir at 600 kPa and temperature
is 300 K. The throat area of the nozzle is 5 cm2
.
Determine:
(a) The ratio of exit-to-throat area and exit area
(b) Given the area ratio in part (a), find the range of back pressure over which the
nozzle is choked. What is the critical pressure and design pressure?
Also, calculate the mass flow rate when the nozzle is choked and at design
conditons.
(c) Determine the mass flow rate for a back pressure of 450 kPa and 500 kPa.
(d) Determine the mass flow rate for a back pressure of 0 kPa.
(e) Plot pressure variation along centerline of nozzle and mark all the points (back
pressures) on it.
(f) Use excel sheet to plot mass variation Vs back pressures and mark all points
on it.

examine the uniform flow and the double flow superposition (flow over the cylinder) for the two-dimensional, incompressible, irrotational flow.
A) flow funcion and velocity potantial.
B) velocity field.
C) stopping points.
D) roller surface.
E) surface pressure distribution.
F) tensile force on the circular cylinder.
G) lifting force on the circular cylinder.

2. An engineer doing an audit finds that liquid water from a process enters the cooling tower at 80 F and with a volumetric flow of 25 gpm and exits at 70 F. Air enters the tower at 80 F and relative humidity of 70% . Air exits the tower at 90 F and 90% relative humidity. The tower does not use make up water.

Determine:

a. The air inlet and outlet conditions in the table

b. Required air flow (cfm)
c. Amount of water at the outlet (not equal to the inlet) (gpm).
d. Heat removed to water

As part of the Project Scope Statement of a house construction project, prepare the detailed
Milestone Schedule (Baseline Milestone – Date) by arranging the following activity
items/milestones in a proper sequence from No. 1 to 15, assuming the first milestone date as 05-
01-2020 and the last as 30-09-2020. Assume the dates in between corresponding to the various
milestones which are given in no particular order: Foundation complete, Excavation complete,
Permits approved & construction begins, Contract signed, Design complete, Framing complete,
Roofing complete, Architectural design started, Final inspection and acceptance by Owners,

Interior finish, Exterior finish, Landscaping complete, HVAC system installed, Plumbing-
electrical-mechanical passed, Plumbing-electrical-mechanical installed.

A central receiver in a solar power plant absorbs a concentrated solar flux from heliostats. However, losses from free convection and radiation lowers the collection efficiency. Consider a receiver with a diameter of 7 m and a height of 12 m that has an emissivity of 0.25 and a surface temperature of 800 K. If the solar flux is 100,000 W/m2, find the collection efficiency. The ambient air and surroundings are at a temperature of 300 K. Assume the curvature of cylinder has a negligible effect on boundary layer development and use the Churchill and Chu correlation to determine the Nusselt number.

1- In a system with outdoor air for ventilation:
(a) the load on coil is equal to the load on building
(b) the load on building is greater than the load on coil
(c) the load on building is less than the load on coil
(d) the Coil ADP is less than room ADP.

2- Evaporative cooling systems are:
(a) attractive for hot and humid climates
(b) attractive for hot and dry climates
(c) ideal for comfort applications
(d) ideal for several industrial applications

3- Selection of a suitable air conditioning system depends on:
(a) Type of the building
(b) Initial and running costs
(c) Reliability and serviceability
(d) All of the above

3- Match the following:
(a) A large precision laboratory a. Variable air volume system
(b) Perimeter zone of a building b. Constant air volume system
(c) Simultaneous cooling and heating c. Multiple zone, single duct system
(d) A large building complex d. Dual duct system

4- A dedicated outside air unit is used to pre-cool 2,500 CFM(1.18m3 /s) of outside air at
31 °C DB and 85% relative humidity to 15.5 °C DB, 14 °C WB. What is the quantity of
water removed by the coil in GPM?
(a) 0.29 ?PM
(b) 0.33 ?PM
(c) 2.9 ?PM
(d) 2.4 ?PM

5- Which of the following statements are TRUE?
(a) Compared to central systems, the initial cost of a unitary system is less
(b) Unitary systems can be installed quickly and their operation is relatively simple
(c) Unitary systems consume less power compared to central systems of same capacity
(d) Unitary systems are ideal for retrofitting applications

6-Unitary refrigerant based systems are:
(a) used for very small capacities only
(b) are available only for cooling applications
(c) couldnot factory assembled with a performance guaranteed by the manufacturer
(d) also called as package units.

7- State which of the following statements are TRUE?
(a) By improving the internal air movement, the energy consumption of the air
conditioning system can be reduced substantially
(b) By increasing air movement, the thermostat of the air conditioning system can be set at a lower temperature
(c) By increasing air movement, the thermostat of the air conditioning system can be
set at a higher temperature
(d) Solar chimneys are ideal under all conditions

8- valves that can be used for shutoff duty:
(a) butterfly,
(b) gate,
(c) ball
(d) All of the above.

9- A single zone, single duct, constant volume system:
(a) used for both cooling and heating simultaneously
(b) The cooling capacity is controlled by controlling the supply air temperature
(c) not suitable when the space conditions have to be controlled precisely
(d) can be used for large single rooms only

10- Dual duct systems are:
(a) provide either cooling or heating
(b) constant air volume systems
(c) energy efficient
(d) occupy more space compared to single duct systems

11-In all- water system of centeral air conditioning system
(a) Cooling medium is chilled water or brine water and not direct refrigerant
(b) The cooling medium may be supplied from a source away from the conditioned
space
(c) The cooling medium may be circulated through the coils of an air terminal
(d) All the above are true

12-In Dual-conduit system of All-Air system of air conditioning
(a) There are two separate air streams
(b) One of the two conduit is permanent by supplying cold and variable air volume for
fluctuating internal and solar load
(c) One of the two conduit supplies constant air volume but variable temperature air
for varying building transmission losses
(d) All of the above statements are true

13-Factors for selection of air conditioning system are
(a) Purpose, location, orientation, and shape of the space or building
(b) Temperature, humidity, wind, exposure to sun and shade of environments of the
space or building
(c) Occupancy, lighting, and other heat exchanges and heat storage capability
(d) All of the above.

14- Which of the following statements are TRUE?
a) All water systems are suitable in buildings requiring individual room control
b) In an air-water system, all the latent load on the building is handled by the primary
air only
c) Dual duct systems are constant air volume systems
d) In all air systems, it is sometimes possible to switch of the cooling coil and use only
outdoor air for air conditioning
e) Variable air volume systems occupy less space compared to constant volume systems

15- For air conditioning the operation theater in a hospital, the percentage of outside air
in the air supplied is:
(a) Zero.
(b) 20
(c) 50
(d) 100.

16- The minimum temperature to which water can be cooled in a cooling tower is:
(a) Dew point temperature of air
(b) Wet bulb temperature of air
(c) Dry bulb temperature of air
(d) Ambient air temperature.

17- The central air conditioning system has ___________ overall efficiency as compared
to individual systems.
(a) Same
(b) Lower
(c) Higher
(d) None of these

18- The choice of chiller determines how the facility is prepared. Examples of parameters
that determine the chiller are:
(a) Electrical requirements
(b) Ease of installation (air-cooled chillers are easier to set up)
(c) Location or available space
(d) Comfort or process cooling
(e) All of the above

19- Ventilated outdoor air can be used:
(a) for cooling of the buildings throughout the year in all locations
(b) for cooling of the buildings during many days of the year in most of the locations
(c) greater potential for cooling of buildings in hot and humid areas
(d) greater potential for cooling of buildings in hot and dry areas

20- State which of the following statements are TRUE?
a) For effective utilization of outdoor air, both natural and mechanical ventilation
should be used in a building
b) Design of windows and other openings in the buildings plays a major role in
natural ventilation
c) For maximum airflow rate, the openings should be as close to the neutral pressure
level as possible
d) All of the above.

21- In comfort-cooling applications, cooling loads are often satisfied by air handlers
equipped with coils to transfer heat from the conditioned space air to circulating
chilled-water. Heat transferred from the loads can be controlled in a number of
ways:
a) Three-way valve
b) Two-way valve
c) Variable-speed pump
d) All of the above.

22- An air handler supplies 5,000 CFM (2.36m3 /s) at a temperature of 13°C. The air handler
was designed for 1,000 CFM of outside air at 31°C DB and 26°C WB. The remaining
return air from the space is at 25 °C DB and 55% relative humidity. What are the
entering conditions of the air into the coil, in DB and WB?
(a) 26 C ?BT, 20 C ?BT
(b) 26 C ?BT, 15 C ?BT
(c) 29.5 C ?BT, 23.5 C ?BT
(d) 29.5 C ?BT, 24 C ?BT

23- In variable air volume systems:
(a) In single duct, variable air volume systems, the supply air flow rate remains
constant, but the temperature of the supply air is varied depending upon the load
(b) Variable air volume systems generally consume less power compared to constant
volume systems
(c) Variable air volume systems occupy less space compared to constant volume
systems
(d) Variable air volume systems always ensure adequate ventilation and good room
air distribution

24- For air-water system, Which of the following statements are TRUE?
(a) An air-water system uses both air and water in the thermal distribution system
(b) In an air-water system, all the latent load on the building is handled by the
primary air only
(c) In an air-water system, the cooling coil kept in the conditioned space operates
under dry conditions
(d) Compared to all water systems, an air-water system is difficult to maintain

25- For fan coil unit ,Which of the following statements are TRUE?
(a) A fan coil unit is used with all water systems only
(b) A fan coil unit can be used either with an all water system or with an air-water
system
(c) It is possible to control the cooling capacity by controlling either liquid flow rate
or air flow rate in a fan coil unit
(d) A fan coil unit used in an all water system requires a provision for draining the
condensed water

26- For a convector, Which of the following statements are TRUE?
(a) In a convector, heat transfer takes place by forced convection
(b) Convectors are commonly used for heating applications
(c) In a radiator, heat transfer takes place by both radiation and convection
(d) A unit ventilator is a fan coil unit with a provision for fresh air entry

27- For Small unitary systems, Which of the following statements are TRUE?
(a) Small unitary systems have air cooled condensers, while larger systems can be
either air cooled or water cooled
(b) A split type room air conditioner should be used when the room does not have an
exterior wall
(c) A split type air conditioner is more reliable compared to a window air conditioner
(d) It is possible to provide fresh air in a window air conditioner, whereas this is not
possible in a split air conditioner

A gas turbine engine is considered in a race car design. The engine operates on two stages of compression with intercooling and two stages of expansion. The pressure ratio across each stage of the compressor and the turbine is 7. The air enters each stage of the compressor at 300K and each stage of the turbine at 1300K. Using air standard assumptions determine:

Thermal efficiency and back work ratio if no regenerator is used;
Thermal efficiency and back work ratio if a regenerator with effectiveness of 90 % is used