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2 years ago

A technician needs to check the heating operation of a heat pump that has no gauge access ports. The technician should start by:

Engineering

1 answer:

OverLord2011 [107]2 years ago

7 0

The technician should start by checking the temperature rise across the indoor coil.

<h3>Who is a technician?</h3>

This is a person who has skill in a particular area of job. A technician is responsible for repairs and also ensure different equipment and systems are working perfectly.

Hence, the technician should start by checking the temperature rise across the indoor coil.

Learn more about technician here : brainly.com/question/13315405

#SPJ1

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What is the maximum thermal efficiency possible for a power cycle operating between 600P'c and 110°C? a). 47% b). 56% c). 63% d)

Anastasy [175]

Answer:

(b) 56%

Explanation:

the maximum thermal efficiency is possible only when power cycle is reversible in nature and when power cycle is reversible in nature the thermal efficiency depends on the temperature

here we have given T₁ (Higher temperature)= 600+273=873

lower temperature T₂=110+273=383

Efficiency of power cycle is given by =1- $\frac{T2}{T1}$

=1- $\frac{383}{873}$

=1-0.43871

=.56

=56%

5 0

2 years ago

A 2 in. diameter pipe supplying steam at 300°F is enclosed in a 1 ft square duct at 70°F. The outside of the duct is perfectly i

Shkiper50 [21]

Answer:

The value of heat transferred watt per foot length Q = 54.78 Watt per foot length.

Explanation:

Diameter of pipe = 2 in = 0.0508 m

Steam temperature $T_{1}$ = 300 F = 422.04 K

Duct temperature $T_{2}$ = 70 F = 294.26 K

Emmisivity of surface 1 = 0.79

Emmisivity of surface 2 = 0.276

Net emmisivity of both surfaces ∈ = 0.25

Stefan volazman constant $\sigma$ = 5.67 × $10^{-8}$ $\frac{W}{m^{2} K^{4} }$

Heat transfer per foot length is given by

Q = ∈ $\sigma$ A ( $T_{1}^{4} - T_{2} ^{4}$ ) ------ (1)

Put all the values in equation (1) , we get

Q = 0.25 × 5.67 × $10^{-8}$ × 3.14 × 0.0508 × 1 × ( $422.04^{4} - 294.26^{4}$ )

Q = 54.78 Watt per foot.

This is the value of heat transferred watt per foot length.

4 0

3 years ago

A thick steel slab ( 7800 kg/m3 , c 480 J/kg K, k 50 W/m K) is initially at 300 C and is cooled by water jets impinging on one o

Nutka1998 [239]

Answer:

1791 secs ≈ 29.85 minutes

Explanation:

( Initial temperature of slab ) T1 = 300° C

temperature of water ( Ts ) = 25°C

T2 ( final temp of slab ) = 50°C

distance between slab and water jet = 25 mm

<u>Determine how long it will take to reach T2</u>

First calculate the thermal diffusivity

∝ = 50 / ( 7800 * 480 ) = 1.34 * 10^-5 m^2/s

<u>next express Temp as a function of time </u>

T( 25 mm , t ) = 50°C

next calculate the time required for the slab to reach 50°C at a distance of 25mm

attached below is the remaining part of the detailed solution

5 0

3 years ago

What is Back EMF? How does it limits the speed of a permanent magnet DC?

ss7ja [257]

Answer and Explanation:

The DC motor has coils inside it which produces magnetic field inside the coil and due to thus magnetic field an emf is induced ,this induced emf is known as back emf. The back emf always acts against the applied voltage. It is represented by $E_b$

The back emf of the DC motor is given by $E_b=\frac{NP\Phi }{60A}$

Here N is speed of the motor ,P signifies the number of poles ,Z signifies the the total number of conductor and A is number of parallel paths

As from the relation we can see that back emf and speed ar dependent on each other it means back emf limits the speed of DC motor

8 0

2 years ago

Engineering controls are the physical changes that employers make to the work environment or to equipment that make it safer to

____ [38]

Answer:

Engineering Controls. The best engineering controls to prevent heat-related illness is to make the work environment cooler and to reduce manual workload with mechanization. A variety of engineering controls can reduce workers' exposure to heat: Air conditioning, Increased general ventilation , Cooling fans , Local exhaust ventilation at points of high heat production or moisture, Reflective shields to redirect radiant heat , Insulation of hot surfaces Elimination of steam leaks , Cooled seats or benches for rest breaks , Use of mechanical equipment to reduce manual work, Misting fans that produce a spray of fine water droplets.

Hope this helped you!

Explanation:

5 0

3 years ago