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Vsevolod [243]
3 years ago
8

A heat pump with refrigerant-134a as the working fluid is used to keep a space at 25°C by absorbing heat from geothermal water t

hat enters the evaporator at 500C at a rate of 0.065 kg/s and leaves at 40°C. The refrigerant enters the evaporator at 20°C with a quality of 23 percent and leaves at the inlet pressure as saturated vapor. The refrigerant loses 300 W of heat to the surroundings as it flows through the compressor and the refrigerant leaves the compressor at 1.4 MPa at the same entropy as the inlet. Determine: (a) The degrees of subcooling of the refrigerant in the condenser, b)-The mass flow rate of the refrigerant . (c) The heating load and the COP of the pump, and d)-The theoretical minimum power input to the compressor for the same heating load.
Engineering
1 answer:
Leno4ka [110]3 years ago
6 0

Answer:2.88

Explanation:

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3. (9 points) A square-thread power screw is used to raise or lower the basketball board in a gym, the weight of which is W = 10
Bezzdna [24]

Answer:

a) 49.95 watts

b) The self locking condition is satisfied

Explanation:

Given data

weight of the square-thread power screw ( w ) = 100 kg = 1000 N

diameter (d) = 20 mm ,

pitch (p) = 2 mm

friction coefficient of steel parts ( f ) = 0.1

Gravity constant ( g ) = 10 N/kg

Rotation of electric power screwdrivers = 300 rpm

A ) Determine the power needed to raise to the basket board

first we have to calculate T

T = Wtan (∝ + Ф ) * \frac{Dm}{2} ------------- equation 1

Dm = d - 0.5 ( 2) = 19mm

Tan ∝ = \frac{L}{\pi  Dm}  where L = 2*2 = 4

hence ∝ = 3.83⁰

given f = 0.1 , Tan Ф = 0.1.     hence Ф = 5.71⁰

insert all the values into equation 1

T = 1.59 Nm

Determine the power needed using this equation

\frac{2\pi NT }{60}   =  \frac{2\pi * 300 * 1.59}{60}

= 49.95 watts

B) checking if the self-locking condition of the power screw is satisfied

Ф > ∝  hence it is self locking condition is satisfied

3 0
3 years ago
A 150-lbm astronaut took his bathroom scale (aspring scale) and a beam scale (compares masses) to themoon where the local gravit
Nonamiya [84]

Answer:

a) W = 25.5 lbf

b) W = 150 lbf

Explanation:

Given data:

Mass of astronaut = 150 lbm

local gravity = 5.48 ft/s^2

a) weight on spring scale

it can be calculated by measuring force against local gravitational force which is equal to weight of body

W = mg

W = (150 \times 5.48)\times \frac{1 lbm}{32.32 lbm. ft/s^2} = 25.5 lbf

b) As we know that beam scale calculated mass only therefore no change in mass due to variation in gravity

thus W= 150 lbf

7 0
3 years ago
In casting experiments performed using a certain alloy and type of sand mold, it took 170 sec for a cube-shaped casting to solid
poizon [28]

Answer:

Answer for the question is : Solidification time will be same i.e. 170. See attached file for explanation.

Explanation:

Download pdf
7 0
3 years ago
Read 2 more answers
Which of the following has special properties that allow forces and pressure to be distributed evenly?
Thepotemich [5.8K]

Answer:

Fluids

Explanation:

Fluids has special properties that allow forces and pressure to be distributed evenly within them.

  • Fluids are gases and liquids whose intermolecular forces of attraction are generally weak or non-existence.
  • Therefore, when pressure is applied to them, it permeates evenly on all parts.
  • Their ability to tend to randomness makes liquids and gases very viable for distributing pressure.
7 0
3 years ago
It is desired to produce and aligned carbon fiber-epoxy matrix composite having a longitudinal tensile strength of 800 MPa. Calc
Aloiza [94]

Answer:

A certain vehicle loses 3.5% of its value each year. If the vehicle has an initial value of $11,168, construct a model that represents the value of the vehicle after a certain number of years. Use your model to compute the value of the vehicle at the end of 6 years.

Explanation:

5 0
3 years ago
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