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irina1246 [14]
2 years ago
11

The fins attached to a surface are determined to have an effectiveness of 0.9. Do the rate of heat transfer from the surface dec

rease as a result of the addition of these fins?
Engineering
1 answer:
Nesterboy [21]2 years ago
8 0

Answer: The rate of heat transfer decreases.

Explanation:

Fin effectiveness is defined as the ratio of heat transfer rate from a  finned surface to the heat transfer rate from the same surface if there were no fins.  Its  value is expected to be greater than 1.

Having effectiveness  value of 0.9  which is less than 1 indicates that the heat transfer rate will decrease since a fin effectiveness smaller than 1 shows that the  fin acts as insulation (thermal insulation).

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Reduce the force F ij = + (2 5 ) kN to point A(2m,3m) that acts on point B( 3m,5m) - .
Alexxx [7]

Given :

Force, \vec{F}= (2\hat{i} + 5\hat{j})\ kN.

Force is acting at point A( 2 m, 3 m ) and B( 3 m, 5 m )

To Find :

The work done by force F .

Solution :

Displacement vector between point A and B is :

\vec{d} = (3-2)\hat{i} + (5-3)\hat{j}\\\\\vec{d} = \hat{i} + 2\hat{j}

Now, we know work done is given by :

W = \vec{F}.\vec{d}\\\\W= (2\hat{i} + 5\hat{j}).(\hat{i}+\hat{2j})\\\\W = (2\times 1) +( 5\times 2) \ kJ\\\\W = 12 \ kJ

W = 12000 J

Therefore, work done by force is 12000 J .

6 0
2 years ago
Consider a Carnot heat pump cycle executed in a steady-flow system in the saturated mixture region using R-134a flowing at a rat
attashe74 [19]

Answer:

7.15

Explanation:

Firstly, the COP of such heat pump must be measured that is,

              COP_{HP}=\frac{T_H}{T_H-T_L}

Therefore, the temperature relationship, T_H=1.15\;T_L

Then, we should apply the values in the COP.

                           =\frac{1.15\;T_L}{1.15-1}

                           =7.67

The number of heat rejected by the heat pump must then be calculated.

                   Q_H=COP_{HP}\times W_{nst}

                          =7.67\times5=38.35

We must then calculate the refrigerant mass flow rate.

                   m=0.264\;kg/s

                   q_H=\frac{Q_H}{m}

                         =\frac{38.35}{0.264}=145.27

The h_g value is 145.27 and therefore the hot reservoir temperature is 64° C.

The pressure at 64 ° C is thus 1849.36 kPa by interpolation.

And, the lowest reservoir temperature must be calculated.

                   T_L=\frac{T_H}{1.15}

                        =\frac{64+273}{1.15}=293.04

                        =19.89\°C

the lowest reservoir temperature = 258.703  kpa                    

So, the pressure ratio should be = 7.15

8 0
2 years ago
technician a says that dirt bypassing the filter on many common rail injectors can cause an injector to stick open and continuou
NNADVOKAT [17]

Technician a is correct because he says that Many common rail injectors filters can be bypassed by dirt, which can lead to an injector sticking open and continuously fueling a cylinder.

Coalescence is used to separate the water and fuel. To the fuel injector cleaning kit, fasten your air compressor. Diesel engines run at compression ratios that are greater than those of gasoline engines. greater ratio compared to gasoline engines. increased thermal expansion as a result. more fuel energy that is transformed into usable power. The great benefit of using a dry cylinder sleeve is that by quickly installing new sleeves, the cylinder block can be quickly restored to its original specifications. Vacuum drying can be used to get rid of small amounts of water. A nozzle is used to spray the fuel into the vacuum chamber of engines. Air and unsolved free water are taken out of the oil. The fuel is evenly dispersed, which facilitates efficient drying.

Learn more about injectors here:

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3 0
10 months ago
Paragraph summary on airplane history
irga5000 [103]

Answer:The Wright brothers invented and flew the first airplane in 1903, recognized as "the first sustained and controlled heavier-than-air powered flight". ... Airplanes had a presence in all the major battles of World War II. The first jet aircraft was the German Heinkel He 178 in 1939.

Explanation:

4 0
3 years ago
If two statements are inconsistent with each other, at least one of them must be false. a)-True b)-False
olchik [2.2K]

Answer:

a)- True

Explanation:

If two statements are inconsistent with each other it means that they are not telling the same, if they are not telling the same it means that only one of them COULD be true, but there is a third option where the two statements are wrong and non statement is telling the true...so:

If we have two statements inconsistent with each other, AT LEAST one of the statements is false.

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