The Unit Operations Laboratory consists of a Continuous Distillation pilot-plant (Figure 1). The plant is mainly composed of a mash-packing column, pre-heater with electrical resistor, a condenser, feed pump and a double-pipe heat exchanger. The pre-heater is used to heat up the raw material that is fed into the column on a continuous basis. The pre-heating system has not been used since the beginning of lockdown (March 2020). This often has detrimental effects on the performance of the pre-heater. You are required to perform a pre-liminary design study to investigate the extent of loss on the performance. The resister is operated to release 38.3% of its maximum capacity (W) and is used to heat the water to a state of saturated steam at a vapour pressure of 2500 dyn/cm². Pre-Heater AU 2. 8. o M v O 10-3 99 OOO L e: Figure 1. P&ID diagram for a Continuous Distillation pilot-plant. a) Determine the surface (wall) temperature (°C) of the heating resistor using Fig. 2 [Hint: A = ndh + d² b) Estimate the boiling heat transfer coefficient, in W/m². K and determine the percentage reduction if the initial coefficient was 63 000 W/m². K.
The Unit Operations Laboratory consists of a Continuous Distillation pilot-plant (Figure 1). The plant is mainly composed of a mash-packing column, pre-heater with electrical resistor, a condenser, feed pump and a double-pipe heat exchanger. The pre-heater is used to heat up the raw material that is fed into the column on a continuous basis. The pre-heating system has not been used since the beginning of lockdown (March 2020). This often has detrimental effects on the performance of the pre-heater. You are required to perform a pre-liminary design study to investigate the extent of loss on the performance. The resister is operated to release 38.3% of its maximum capacity (W) and is used to heat the water to a state of saturated steam at a vapour pressure of 2500 dyn/cm². Pre-Heater AU 2. 8. o M v O 10-3 99 OOO L e: Figure 1. P&ID diagram for a Continuous Distillation pilot-plant. a) Determine the surface (wall) temperature (°C) of the heating resistor using Fig. 2 [Hint: A = ndh + d² b) Estimate the boiling heat transfer coefficient, in W/m². K and determine the percentage reduction if the initial coefficient was 63 000 W/m². K.
Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
8th Edition
ISBN:9781305387102
Author:Kreith, Frank; Manglik, Raj M.
Publisher:Kreith, Frank; Manglik, Raj M.
Chapter9: Heat Transfer With Phase Change
Section: Chapter Questions
Problem 9.11P
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![DESIGN OF A DOUBLE-PIPE HEAT EXCHANGER
The Unit Operations Laboratory consists of a Continuous Distillation pilot-plant (Figure 1). The plant
is mainly composed of a mash-packing column, pre-heater with electrical resistor, a condenser, feed
pump and a double-pipe heat exchanger. The pre-heater is used to heat up the raw material that is fed
into the column on a continuous basis. The pre-heating system has not been used since the beginning
of lockdown (March 2020). This often has detrimental effects on the performance of the pre-heater.
You are required to perfom a pre-liminary design study to investigate the extent of loss on the
performance. The resister is operated to release 38.3% of its maximum capacity (W) and is used to
heat the water to a state of saturated steam at a vapour pressure of 2500 dyn/cm?.
오오
Pre-Heater
Loo
Figure 1. P&ID diagram for a Continuous Distillation pilot-plant.
a) Determine the surface (wall) temperature (°C) of the heating resistor using Fig. 2
[Hint: A = ndh +
b) Estimate the boiling heat transfer coefficient, in W/m2. K and detemine the percentage
reduction if the initial coefficient was 63 000 W/m2. K.
c) Assuming the air conditiong system at the lab is switched on and the room temperature is
maintined at 53.6°F and the thickness of the pre-heater (glass window) is 2 cm. Estimate the
heat lost (kW/m²) to the surroundings if the convective coefficient of air is 9852 W/m?. K.
d) Calculate the ammount of heat absorbed (W/m²) by the water in the pre-heater.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fdee427e3-8375-4538-8f16-67c4bf9cb053%2F40bd5599-9490-4d89-8029-4de0fef9af99%2Fq6u75np_processed.jpeg&w=3840&q=75)
Transcribed Image Text:DESIGN OF A DOUBLE-PIPE HEAT EXCHANGER
The Unit Operations Laboratory consists of a Continuous Distillation pilot-plant (Figure 1). The plant
is mainly composed of a mash-packing column, pre-heater with electrical resistor, a condenser, feed
pump and a double-pipe heat exchanger. The pre-heater is used to heat up the raw material that is fed
into the column on a continuous basis. The pre-heating system has not been used since the beginning
of lockdown (March 2020). This often has detrimental effects on the performance of the pre-heater.
You are required to perfom a pre-liminary design study to investigate the extent of loss on the
performance. The resister is operated to release 38.3% of its maximum capacity (W) and is used to
heat the water to a state of saturated steam at a vapour pressure of 2500 dyn/cm?.
오오
Pre-Heater
Loo
Figure 1. P&ID diagram for a Continuous Distillation pilot-plant.
a) Determine the surface (wall) temperature (°C) of the heating resistor using Fig. 2
[Hint: A = ndh +
b) Estimate the boiling heat transfer coefficient, in W/m2. K and detemine the percentage
reduction if the initial coefficient was 63 000 W/m2. K.
c) Assuming the air conditiong system at the lab is switched on and the room temperature is
maintined at 53.6°F and the thickness of the pre-heater (glass window) is 2 cm. Estimate the
heat lost (kW/m²) to the surroundings if the convective coefficient of air is 9852 W/m?. K.
d) Calculate the ammount of heat absorbed (W/m²) by the water in the pre-heater.
![Region I
Region II
Maximum
Region IV
| critical) heat |
flux.
Film
Nucleate
boiling
to
Transition
boiling
boiling
Natural
convection
10
Minimum
boiling
Slugs and
heat flux,4
Di
min
to
columns-
Isolated
Region II
bubbles
10
10
30
100
320
1000
AT=T,-T. (C)
Figure 2. Boiling mechanisms for water.
Table 1. Heating Resistor Features.
Features and Benefits
Power rating of 17.0608 Btu/min
• Diameter of 10 mm
Length of 65 mm
Quartz resistance wire for maximum heater life
• TIG-welded end disc prevents contamination and
moisture absorption
Fibreglass lead wire insulation
• Complies with Electrostatic Control Standards
ANSI/ESD S20.20:2014 and BS EN 61340-5-
1:2007
ROHS compliant on restricted hazardous substances
4 (W/m)](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fdee427e3-8375-4538-8f16-67c4bf9cb053%2F40bd5599-9490-4d89-8029-4de0fef9af99%2F5g90fle_processed.jpeg&w=3840&q=75)
Transcribed Image Text:Region I
Region II
Maximum
Region IV
| critical) heat |
flux.
Film
Nucleate
boiling
to
Transition
boiling
boiling
Natural
convection
10
Minimum
boiling
Slugs and
heat flux,4
Di
min
to
columns-
Isolated
Region II
bubbles
10
10
30
100
320
1000
AT=T,-T. (C)
Figure 2. Boiling mechanisms for water.
Table 1. Heating Resistor Features.
Features and Benefits
Power rating of 17.0608 Btu/min
• Diameter of 10 mm
Length of 65 mm
Quartz resistance wire for maximum heater life
• TIG-welded end disc prevents contamination and
moisture absorption
Fibreglass lead wire insulation
• Complies with Electrostatic Control Standards
ANSI/ESD S20.20:2014 and BS EN 61340-5-
1:2007
ROHS compliant on restricted hazardous substances
4 (W/m)
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