Moist air at 55 oF dry bulb temperature and 40% relative humidity is first heated through a heating coil. The air is then adiabatically humidified by saturated water vapor at 4.5 psia. The exit air has a dry bulb temperature of 90 oF and wet bulb temperature 65 oF. Air is supplied at a volume flow rate of 478.5 cfm. Assume sea level pressure throughout. Determine the following.
a) Show the inlet and outlet air condition clearly on the psychrometric chart clearly marking them as 1 and 2 respectively.
b) Show the sensible heating process and humidification process on the psychrometric chart clearly marking them. Draw the overall process line.
c) Calculate the heat transfer rate of the heating coil. Show your calculation.
d) Calculate the mass flow rate of the water vapor. Show your calculation.
e) What is the SHF value? Show clearly how you obtained it.
In: Mechanical Engineering
1.Write the Bernoulli equation and state all the assumptions used in its derivation.
2.Write the vector form of the conservation of momentum equation for a control volume that is moving with a constant velocity.
3.) Water is flowing in a fire hose with a velocity of 1.0 m/s and a pressure of 200000 Pa. Use the Bernoulli equation to calculate the velocity of the water exiting the nozzle. Note: Derive the expression before plugging in numbers and clearly state all your assumptions.
4.Through a refinery, fuel ethanol is flowing in a pipe at a velocity of 1 m/s and a pressure of 101300 Pa. The refinery needs the ethanol to be at a pressure of 2 atm (202600 Pa) on a lower level. How far must the pipe drop in height in order to achieve this pressure? Assume the velocity does not change. (Hint: Use the Bernoulli equation. The density of ethanol is 789 kg/m3 ). Derive the expression before plugging in numbers.
In: Mechanical Engineering
An air-conditioning plant is designed to maintain a room at a
condition of 20oC dry bulb and specific humidity 0.0079 when the
outside condition is 30oC dry bulb and 40% percentage saturation
and the corresponding heat gains are 18000 W (sensible) and 3600
(latent). The supply air contains one-third outside air by mass and
the supply temperature is to be 15oC dry bulb. The plant consists
of a mixing chamber for fresh and recirculated air, an air washer
with chilled spray water with an efficiency of 80%, an after heater
battery and supply fan. Neglecting temperature changes in fan and
ducting, calculate:
a. The mass flow rat of supply air necessary;
b. The specific humidity of the supply air;
c. The cooling duty of the washer;
d. The heating duty of the after heater
(use the psychrometric chart assuming the barometric pressure is
1.001325 bar)
In: Mechanical Engineering
Composites:
In: Mechanical Engineering
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what are the four different mechanisms in a steam engine? explain them.
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ABCD is a four bar chain with link AD fixed. The lengths of the
links are AB = 62.5 mm;
BC = 175 mm; CD = 112.5 mm; and AD = 200 mm. The crank AB rotates
at 48 rad/s
clockwise. Draw the velocity and acceleration diagram when angle
BAD = 60° and B and
C lie on the same side of AD. Find the angular velocity and angular
acceleration of links
BC and CD.
In: Mechanical Engineering
(a) |
In a couple of sentences with clear annotated sketches explain the following terms:
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A horizontal jet of oil (SG = 0.6) strikes a curved blade that turns the flow through an angle of 1800. The jet area is 1000 mm2 and its speed from a stationary nozzle is 35 m/s. The blade is moving toward the nozzle at 15 m/s. Determine the force on the blade from the jet (a) in horizontal direction, Rx in kN and (b) in vertical direction, Ry in kN. [Consider the relative jet velocity in calculations]
In: Mechanical Engineering
Air cargo has experienced a renaissance in the last several years because of skyrocketing international e-commerce amid heightened consumer expectations and reduced oil prices. Additionally, airfreight has become increasingly competitive against other modes of transportation in recent years. Discuss how air cargo should be forecast in 20 years and develop a schematic diagram on the future plan of cargo infrastructure with consideration of air traffic forecast
In: Mechanical Engineering
The sample measurements for Aluminum, Copper and Nylon
have the same length, width, and thickness. While the length is
76.5mm and the width is 19.5mm, the thickness of these samples are
about 0.127 mm.
How might these specimens behave differently if they were
thick?
In: Mechanical Engineering
A 4500 lb SUV is traveling at 65 mph when it strikes a staged attenuator designed to produce three different energy dissipation rates. For the first 6 ft, the attenuator produces a force of 20,000 lb on the impacting vehicle. The second stage is 4 ft long and produces a deceleration force of 40,000 lb. “How long does the attenuator’s 3rd stage have to be to safely stop the SUV if its deceleration force is 60,000 lb. Construct the a-s, a-t, and v-t curves for this impact. (Hint: safely stopping the SUV means the vehicle stops before using up the 3rd stage.)
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You have just joined the design and development group at Panasonic, Inc. The first task you are given is to work on the design of a thermal system to anneal TV glass screens. Each screen is made of semi-transparent glass and weighs 10 kg. You need to heat it from a room temperature of 25°C to 1100°C, maintain it at this temperature for 15 minutes, and then cool slowly to 500°C, after which it may be cooled more rapidly to room temperature. The allowable rate of temperature change with time, ∂T/∂t, is given for heating, slow cooling, and fast cooling processes. Any energy source may be used and high production rates and uniform annealing are desired. (a) Give the sketch of a possible conceptual design for the system and of the expected temperature cycle. Briefly give reasons for your choice. (b) List the requirements and constraints in the problem. (c) Give the location and type of sensors you would use to control the system and ensure safe operation. Briefly justify your choices (d) Outline a simple mathematical model to simulate the process.
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Discuss the processes for manufacturing components of complicated shapes in larger quantities.
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State the importance of using superheaters and reheaters in standalone steam power plants and in combined cycle power plants. Make a short comparison
please compare them to each other.
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