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3 years ago

Explain how safety devices inside your car help keep you safe?

Engineering

1 answer:

Lesechka [4]3 years ago

5 0

Safety devices can help decrease force taken during a crash they also keep u in place and protected overall

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Refrigerant 134a at p1 = 30 lbf/in2, T1 = 40oF enters a compressor operating at steady state with a mass flow rate of 200 lb/h a

Mazyrski [523]

Answer:

a) $\mathbf{Q_c = -3730.8684 \ Btu/hr}$

b) $\mathbf{\sigma _c = 4.3067 \ Btu/hr ^0R}$

Explanation:

From the properties of Super-heated Refrigerant 134a Vapor at $T_1 = 40^0 F$ , $P_1 = 30 \ lbf/in^2$ ; we obtain the following properties for specific enthalpy and specific entropy.

So; specific enthalpy $h_1 = 109.12 \ Btu/lb$

specific entropy $s_1 = 0.2315 \ Btu/lb.^0R$

Also; from the properties of saturated Refrigerant 134 a vapor (liquid - vapor). pressure table at $P_2 = 160 \ lbf/in^2$ ; we obtain the following properties:

$h_2 = 115.91 \ Btu/lb\\\\ s_2 = 0.2157 \ Btu/lb.^0R$

Given that the power input to the compressor is 2 hp;

Then converting to Btu/hr ;we known that since 1 hp = 2544.4342 Btu/hr

2 hp = 2 × 2544.4342 Btu/hr

2 hp = 5088.8684 Btu/hr

The steady state energy for a compressor can be expressed by the formula:

$0 = Q_c -W_c+m((h_1-h_e) + \dfrac{v_i^2-v_e^2}{2}+g(\bar \omega_i - \bar \omega_e)$

By neglecting kinetic and potential energy effects; we have:

$0 = Q_c -W_c+m(h_1-h_2) \\ \\ Q_c = -W_c+m(h_2-h_1)$

$Q_c = -5088.8684 \ Btu/hr +200 \ lb/hr( 115.91 -109.12) Btu/lb \\ \\$

$\mathbf{Q_c = -3730.8684 \ Btu/hr}$

b) To determine the entropy generation; we employ the formula:

$\dfrac{dS}{dt} =\dfrac{Qc}{T}+ m( s_1 -s_2) + \sigma _c$

In a steady state condition $\dfrac{dS}{dt} =0$

Hence;

$0=\dfrac{Qc}{T}+ m( s_1 -s_2) + \sigma _c$

$\sigma _c = m( s_1 -s_2) - \dfrac{Qc}{T}$

$\sigma _c = [200 \ lb/hr (0.2157 -0.2315) \ Btu/lb .^0R - \dfrac{(-3730.8684 \ Btu/hr)}{(40^0 + 459.67^0)^0R}]$

$\sigma _c = [(-3.16 ) \ Btu/hr .^0R + (7.4667 ) Btu/hr ^0R}]$

$\mathbf{\sigma _c = 4.3067 \ Btu/hr ^0R}$

5 0

3 years ago

Join the pad let <br><br> https://pad let.com/56021812/8g75510tedza5v2a

labwork [276]

What the brxh is a parley

7 0

3 years ago

Read 2 more answers

The thermal conductivity of a solid depends upon the solid’s temperature as k = a T+b where a and b are constants. The temperatu

Alexandra [31]

Answer:

Answer is Option (e) - None of these

Explanation:

The step by step derivation from the fourier's law of heat conduction is as shown in the attachment below.

Where K = thermal conductivity

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4 years ago

Which is a drawback of solar energy

alexira [117]

Answer:

Drawbacks include that it is costlier than other clean energies. Another thing is that when it isnt sunny you wont get as much energy

8 0

3 years ago

Along with refining craft skills another way to increase the odds for career advancement is to

Xelga [282]

The acquisition of additional certifications with a personal refined craft skills can increase the odds for career advancemen.

<h3>What is a career advancement?</h3>

An advancement is achieved in a career if a professional use their skill sets, determination or perserverance to achieve new career height.

An example of a career advancement is when an employee progresses from entry-level position to management and transits from an occupation to another.

Therefore, the Option A is correct.