Engineering, 19.03.2020 23:17 marrizza7

In a manufacturing plant that produces cosmetic products, glycerin is being heated by flowing through a 25-mm-diameter and 20-m-long tube. With a mass flow rate of 0.5 kg/s, the flow of glycerin enters the tube at 25°C. The tube surface is maintained at a constant surface temperature of 140°C. Evaluate the properties for glycerin at 30°C. The properties of glycerin at 30°C are:

Answers: 3

Show answers

Answers

Answer from: FlayMaster101

Total rate of heat transfer for the tube. Q = 13.1 kW

Explanation:

Given data:

Diameter of the tube, D = 0.025 m

Lengthofthetube, L=IOm

Mass flow rate, m = 0.5 kg/s

Glycerin inlet temperature, 1 = 25°C

Tube surface temperature, 7 = 140°C

The expression for the outlet temperature Td is

(see image 1 for equation).

where I, - Heat transfer coefficient

A, - Heat transfer surface area

m.- Mass flow rate

Cp- Specific heat at constant pressure

Properties of glycerine:

Density, = 1258 kg/rn

Specific heat at constant pressure, c, —2447 i/kg. K

Thermal conductivity, k = 0.2860 W/m. K

Dynamic viscosity. p = 0.6582 kg/rn. s

Prandtl number. Pr = 5631

Now Reynolds number can be calculated using the equation,

(See image 2).

Since the value is less than 2300, the flow is laminar.

Now, the hydrodynamic entry length is given by,

Lk = 0.05 Re D

= 0.05 x 38.69 X 0.025

= 0.04836 m

Thermal entry length is given by.

Lt= Lh x Pr

0,04X36x5631

= 272.32 m

As the thermal entry length is greater than the given tube length. the flow is not thermally

developed but developing. Therefore, the average Nusselt number for the thermal entrance

region can be determined using the following equation.

See image 3.

The convective heat transfer coefficient.

h= k•Nu /D .

= 152.29 W/m2.K

Heat transfer surface area.

A = πDL

= 0.7854 m2

The mean temperature at outlet.

see image 4 for explanation.

Hence the mean temperature at outlet of the tube. I = 35.7C1

The total rate of heat transfer for the tube.

Q = mcp (To - T1)

=O.5x2447x(35.71—25)

= O.5x2447x10.7

= 13091.45 W

= 13.1 kW

Therefore, the total rate of heat transfer for the tube. IQ = 13.1 kW

In a manufacturing plant that produces cosmetic products, glycerin is being heated by flowing throug

Answer from: Quest

answer:

i dont know but you should start brainstorming ideas like how would you post them

explanation:

Answer from: Quest

Idon’t do engeneering classes sorry

Another question on Engineering

Engineering, 04.07.2019 18:10

Apump is used to circulate hot water in a home heating system. water enters the well-insulated pump operating at steady state at a rate of 0.42 gal/min. the inlet pressure and temperature are 14.7 lbf/in.2, and 180°f, respectively; at the exit the pressure is 60 lbf/in.2 the pump requires 1/15 hp of power input. water can be modeled as an incompressible substance with constant density of 60.58 lb/ft3 and constant specific heat of 1 btu/lb or. neglecting kinetic and potential energy effects, determine the temperature change, in °r, as the water flows through the pump.

Answers: 1

Answer

Engineering, 04.07.2019 19:10

A)-explain briefly the importance of standards in engineering design. b)- what is patent? c)-explain the relationship between these standards: b.s. and b.s.en d)- in engineering design concepts, types of loads and how they act are important factors. explain.

Answers: 3

Answer

Engineering, 04.07.2019 19:10

Analyze the factors that influence the choice between the following pairs of processes to make the products indicated: i) sand casting versus die casting of an electric-motor housing ii) thread rolling versus machining of a bolt for high-strength application. (co3/c5)

Answers: 3

Answer

Engineering, 04.07.2019 19:20

Acommercial grade cubical freezer, 4 m on a side, has a composite wall consisting of an exterior sheet of 5.0-mm thick plain carbon steel (kst= 60.5 w/m k), an intermediate layer of 100-mm thick polyurethane insulation (kins 0.02 w/m k), and an inner sheet of 5.0- mm thick aluminium alloy (kal polyurethane insulation and both metallic sheets are each characterized by a thermal contact resistance of r 2.5 x 104 m2 k/w. (a) what is the steady-state cooling load that must be maintained by the refrigerator under conditions for which the outer and inner surface temperatures are 25°c and -5°c, respectively? (b) for power saving purpose, which wall material should be increased/reduced in. thickness in order to reduce 50% of the cooling load found in part (a)? redesign the thickness of the proposed material. 177 w/m-k). adhesive interfaces between the q=575.93 w

Answers: 2

Answer

You know the right answer?

In a manufacturing plant that produces cosmetic products, glycerin is being heated by flowing throug...

Questions