answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Tanya
23 days ago
5

An overhead 25m-long, uninsulated industrial steam pipe of 100-mm diameter, is routed through a building whose walls and air are

at25C. pressurized steam matains a pipe surface temperature of 150C and the coeff of nature convection h = 10W/m^2K. the surface emissivity e= 0.8
1. what is the rate of heat loss from the steam line?
2.if the steam is gernerated in a gas-fired boiler operating at efficenty of 0.9, and natural gas is priced at C=0.02 per MJ, what is the annual cost of heat loss from line?
Engineering
1 answer:
Viktor [230]23 days ago
8 0

Answer:

1) q=18414.93 W

2) C=12920$

Explanation:

Provided information:

Length of the pipe L=25m

Diameter of the pipe D=100mm =0.1 m

Temperature of air T_{s1}=T_{\infty1} }=25°C.....= 298.15k

Surface temperature of the pipe T_{s2}=150°C.....=423.15k

Emissivity of the surface e= 0.8

Efficiency of the boiler η=0.90

Price of natural gas Cg=$0.02 per MJ

1) Combined total heat loss and radiative heat loss

          q=q_{conv} +q_{rad}

          q=A[h(T_{s2}-T_{s1})+eб(T_{s2}^4-T_{s1}^4)]....... (1)

б=5.67×10^-8 W/m^2K^4 (Boltzmann constant)

Area A =L·D·π=25·0.1·π=7.85 m^2

By substituting these values in equation (1)

q=18414.93 W

2) If the boiler runs continuously, the yearly energy loss will be

               E=q·t

                  =18414.93·3600·24·365

                  =5.81×10^11 J

   To calculate the energy consumption of the furnace

               Ef =E/η

                  =6.46×10^5 MJ

   Annual expenses

                  C=Cg·Ef

                    =12920$

You might be interested in
A test machine that kicks soccer balls has a 5-lb simulated foot attached to the end of a 6-ft long pendulum arm of negligible m
choli [191]

Answer:

a) v₂ = 26.6 ft/s

b) v₂ = 31.9 ft/s

Explanation:

a) Applying the principle of energy conservation for the soccer arm from the point of impact to its lowest point:

mgh=\frac{1}{2} mv^{2} \\v=\sqrt{2gh} =\sqrt{2*32.2*6} =19.66ft/s

The ball's velocity in the tangential direction is given by:

v₂*sinθ = v₁*sin30

With the values:

if v₁ = 0

θ = 0º

The restitution coefficient is:

e=\frac{v_{2}*cosO-v_{2}cos30 }{v*cos30-(-v_{1}*cos30 )} \\0.8=\frac{v_{2}cos0-v_{2}*cos30 }{19.66*cos30-(0*cos30)} \\v_{2} =\frac{v_{2}-13.6 }{cos30}

where O=θ

The aggregate momentum equation is:

mv-mv_{1} =mv_{2} +mv_{2} cos(O+30)\\, where O = θ

mv-mv_{1} =m(\frac{v_{2}-13.6 }{cos30} )+mv_{2} cos(O+30)

When we incorporate gravitational acceleration:

mgv-mgv_{1} =mg(\frac{v_{2}-13.6 }{cos30} )+mgv_{2} cos(O+30)\\5*19.66-1*0=5*(\frac{v_{2}-13.6 }{cos30} )+1*v_{2} cos(O+30)

Isolating v₂ results in:

v₂ = 26.6 ft/s

b) To find the ball's velocity, we utilize:

v₂ * sinθ = v₁ * sin30

if v₁ = 10 ft/s

then v₂ * sinθ = 10 * sin30

thus sinθ = 5/v₂

The restitution coefficient remains:

e=\frac{v_{2}*cosO-v_{2}cos30 }{v*cos30-(-v_{2}*cos30) } \\0.8=\frac{v_{2}cosO-v_{2}cos30 }{19.66*cos30-(-10*cos30)} \\v_{2} =\frac{v_{2}cos30-20.55}{cos30}

where O = θ

mgv-mgv_{1} =mgv_{2} +mgv_{2} cos(O+30)\\5*19.66-1*0=5v_{2} +v_{2} cos(O+30)\\98.3=5v_{2}+v_{2} cosOcos30-v_{2} sinOsin30

Solving for v₂ yields:

v₂ = 31.9 ft/s

6 0
22 days ago
Consider a rectangular fin that is used to cool a motorcycle engine. The fin is 0.15m long and at a temperature of 250C, while t
Kisachek [217]

Answer:

q' = 5826 W/m

Explanation:

Given:-

- The length of the fin in question, L = 0.15 m

- The fin's surface temperature, Ts = 250°C

- The velocity of free stream air, U = 80 km/h

- The air temperature, Ta = 27°C

- The flow is parallel over both sides of the fin, assuming turbulent flow conditions throughout.

Find:-

What is the heat removal rate per unit width of the fin?

Solution:-

- Steady state conditions are assumed, along with negligible radiation and turbulent flow conditions.

- From Table A-4, we gather air properties (T = 412 K, P = 1 atm ):

    Dynamic viscosity, v = 27.85 * 10^-6 m²/s  

    Thermal conductivity, k = 0.0346 W / m.K

    Prandtl number Pr = 0.69

- Compute the Nusselt Number (Nu) corresponding to - turbulent conditions - using the relevant relationship as follows:

                          Nu = 0.037*Re_L^\frac{4}{5} * Pr^\frac{1}{3}

Where,    Re_L: Average Reynolds number for the entire length of fin:

                          Re_L = \frac{U*L}{v} \\\\Re_L = \frac{80*\frac{1000}{3600} * 0.15}{27.85*10^-^6} \\\\Re_L = 119688.80909

Consequently,

                         

Nu = 0.037*(119688.80909)^\frac{4}{5} * 0.69^\frac{1}{3}\\\\Nu = 378

- The convective heat transfer coefficient (h) can now be derived from:

                          h = \frac{k*Nu}{L} \\\\h = \frac{0.0346*378}{0.15} \\\\h = 87 \frac{W}{m^2K}

- The heat loss rate q' per unit width can be established using the convection heat transfer formula and should be multiplied by (x2) since the airflow is present on both sides of the fin:

                          q' = 2*[h*L*(T_s - T_a)]\\\\q' = 2*[87*0.15*(250 - 27)]\\\\q' = 5826\frac{W}{m}

- Ultimately, the heat loss per unit width from the rectangular fin is q' = 5826 W/m

- The thermal loss per unit width (q') attributed to radiation:

                  q' = 2*a*T_s^4*L

Where, a signifies the Stefan-Boltzmann constant = 5.67*10^-8

                  q' = 2*5.67*10^-^8*(523)^4*0.15\\\\q' = 1273 \frac{W}{m}

- It is observed that radiation losses are not insignificant, accounting for 20% of thermal loss by convection. As the emissivity (e) of the fin is unspecified, this value is dismissed from the calculations as it pertains to the provided information.

7 0
4 days ago
The most flexible and mobile method of supplying our need for mechanical energy has been the internal-__________ engine. (10 let
Daniel [215]

Answer:

Combustion

Explanation:

This relates to an internal-combustion engine.

4 0
15 days ago
Read 2 more answers
PDAs with two stacks are strictly more powerful than PDAs with one stack. Prove that 2-stack PDAs are not a valid model for CFLs
iogann1982 [279]

Answer:

?pooooooooooooooooooooooop

Explanation:

?pooooooooooooooooooooooop

6 0
2 days ago
Number pattern Write a recursive method called print Pattern() to output the following number pattern. Given a positive integer
alex41 [274]

Response:

Refer to the explanation

Clarification:

Code:

import java.util.Scanner;

public class NumberPattern {

public static int x, count;

public static void displayNumPattern(int num1, int num2) {

if (num1 > 0 && x == 0) {

System.out.print(num1 + " ");

count++;

displayNumPattern(num1 - num2, num2);

} else {

x = 1;

if (count >= 0) {

System.out.print(num1 + " ");

count--;

if (count < 0) {

System.exit(0);

}

displayNumPattern(num1 + num2, num2);

}

}

}

public static void main(String[] args) {

Scanner scnr = new Scanner(System.in);

int num1;

int num2;

num1 = scnr.nextInt();

num2 = scnr.nextInt();

displayNumPattern(num1, num2);

}

}

See attached example output

3 0
19 days ago
Read 2 more answers
Other questions:
  • A sign erected on uneven ground is guyed by cables EF and EG. If the force exerted by cable EF at E is 46 lb, determine the mome
    13·1 answer
  • Degreasers can be broken down into two main categories
    9·2 answers
  • Given two input integers for an arrowhead and arrow body, print a right-facing arrow. Ex: If the input is 0 1, the output is
    8·1 answer
  • 3.24 Program: Drawing a half arrow (Java) This program outputs a downwards facing arrow composed of a rectangle and a right tria
    12·1 answer
  • An 80-L vessel contains 4 kg of refrigerant-134a at a pressure of 160kPa. Determine (a) the temperature, (b) the quality, (c) th
    11·1 answer
  • A certain full-wave rectifier has a peak output voltage of 30 V. A 50 mF capacitor-input filter is connected to the rectifier. C
    6·1 answer
  • All MOS devices are subject to damage from:________
    7·1 answer
  • 1 At a certain location, wind is blowing steadily at 10 m/s. Determine the mechanical energy of air per unit mass and the power
    11·1 answer
  • cubical tank 1 meter on each edge is filled with water at 20 degrees C. A cubical pure copper block 0.46 meters on each edge wit
    6·1 answer
  • A pipe in a district heating network is transporting over-pressurized hot water (10 atm) at a mass flow of 0.5 kg/s. The pipe is
    14·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!