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FromTheMoon [43]

3 years ago

12

During January, at a location in Alaska winds at -20°C can be observed, However, several meters below ground the temperature rem

ains at 11°C. An inventor claims to have devised a power cycle working between these temperatures having a thermal efficiency of 10%.
Investigate this claim.

(a) What is the maximum thermal efficiency for these conditions?

(b) Is the inventor's claim possible?

1 answer:

maw [93]3 years ago

4 0

Answer:

a) $\eta_{th} = 10.910\,\%$ , b) Yes.

Explanation:

a) The maximum thermal efficiency is given by the Carnot's Cycle, whose formula is:

$\eta_{th} =\left(1-\frac{253.15\,K}{284.15\,K} \right) \times 100\,\%$

$\eta_{th} = 10.910\,\%$

b) The claim of the inventor is possible since real efficiency is lower than maximum thermal efficiency.

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Refrigerant-134a enters the expansion valve of a refrigeration system at 120 psia as a saturated liquid and leaves at 20 psia. D

Shkiper50 [21]

Solution :

$P_1 = 120 \ psia$

$P_2 = 20 \ psia$

Using the data table for refrigerant-134a at P = 120 psia

$h_1=h_f=40.8365 \ Btu/lbm$

$u_1=u_f=40.5485 \ Btu/lbm$

$T_{sat}=87.745^\circ F$

∴ $h_2=h_1=40.8365 \ Btu/lbm$

For pressure, P = 20 psia

$h_{2f} = 11.445 \ Btu/lbm$

$h_{2g} = 102.73 \ Btu/lbm$

$u_{2f} = 11.401 \ Btu/lbm$

$u_{2g} = 94.3 \ Btu/lbm$

$T_2=T_{sat}=-2.43^\circ F$

Change in temperature, $\Delta T = T_2-T_1$

$\Delta T = -2.43-87.745$

$\Delta T=-90.175^\circ F$

Now we find the quality,

$h_2=h_f+x_2(h_g-h_f)$

$40.8365=11.445+x_2(91.282)$

$x_2=0.32198$

The final energy,

$u_2=u_f+x_2.u_{fg}$

$=11.401+0.32198(82.898)$

$=38.09297 \ Btu/lbm$

Change in internal energy

$\Delta u= u_2-u_1$

= 38.09297-40.5485

= -2.4556

5 0

2 years ago

ASAP correct answer plss When you are driving, if you see this traffic sign it means

vlabodo [156]

Answer:

C

Explanation:

5 0

3 years ago

A fluid of specific gravity 0.96 flows steadily in a long, vertical 0.71-in.-diameter pipe with an average velocity of 0.90 ft/s

KengaRu [80]

Answer:

0.00650 Ib s /ft^2

Explanation:

diameter ( D ) = 0.71 inches = 0.0591 ft

velocity = 0.90 ft/s ( V )

fluid specific gravity = 0.96 (62.4 ) ( x )

change in pressure ( P ) = 0 because pressure was constant

viscosity = (change in p - X sin∅ ) $D^{2}$ / 32 V

= ( 0 - 0.96( 62.4) sin -90 ) * 0.0591 ^2 / 32 * 0.90

= - 59.904 sin (-90) * 0.0035 / 28.8

= 0.1874 / 28.8

viscosity = 0.00650 Ib s /ft^2

8 0

3 years ago

Read 2 more answers

The device whose operation closely matches the way the clamp-on ammeter works is

Ivanshal [37]

Answer:

The answer is

C. Split phase motor

Explanation:

Clamp meters rely on the principle of magnetic induction to make non contact AC current measurements. Electric current flowing through a wire produces a magnetic field.

Which is similar to basic mode of operation of electric motor and split phase motor is a type of electric motor.

What is a a clamp on meter?

Clamp meters are electrical testers which have wide jaws that are able to clamp around an electrical conductor. Originally designed as a single purpose tool for measuring AC current, clamp meters now include inputs for accepting test leads and other probes that support a wide range of electrical measurements, the jaws of a clamp meter permit work in tight spaces and permits current measurements on live conductors without circuit interruption.

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2 years ago

Types of technology include:

Anastaziya [24]

The answer is D-all choices

3 0

2 years ago