A concentric tube heat exchanger for cooling lubricating oil is comprised of a thin-walled inner tube...
A concentric tube heat exchanger for cooling lubricating oil is
comprised of a thin-walled inner tube of 25 mm diameter carrying water and an outer tube
of 45 mm diameter carrying the oil. The mass flow rates of both fluids are 0.1 kg/s. The
exchanger operates in counter-flow with an overall heat transfer coefficient of 60 W/m2
Homework Answers
Heat Exchanger:
This device is used to implement the process of heat exchange between two fluids that are at different temperatures and separated by a solid wall.
When the two fluids are separated by concentric tubes and two fluids flow in opposite direction the device is termed as counter flow concentric tube heat exchanger.
Apply overall energy balance on the hot fluid to find the heat transfer. Then apply the energy balance on the cold fluid to find the outlet temperature of cold fluid. Use the LMTD method and calculate the length of the exchanger.
Write the expression for energy balance of hot fluid.
Here, the mass flow rate of hot fluid is 
,the specific heat constant of hot fluid is 
, the inlet temperature of hot fluid is 
, and the outlet temperature of the hot fluid is 
.
Write the expression for energy balance of cold fluid.
Here, the mass flow rate of cold fluid is 
,the specific heat constant of cold fluid is 
, the inlet temperature of cold fluid is 
, and the outlet temperature of the cold fluid is 
.
Write the expression for LMTD for counter flow heat exchanger.
Find the length of the Counter flow heat exchanger using the following relation:
Here, the overall heat transfer coefficient is 
, the diameter of the tube is 
, and the length of the tube is 
.
Draw the schematic diagram of the counter flow heat exchanger.
Properties for Hot Fluid:
Density of the fluid,
Specific heat of hot fluid,
Viscosity of hot fluid is
Thermal conductivity of hot fluid is
Prandtl number of hot fluid is
Properties for Cold Fluid:
Specific heat of cold fluid is
Viscosity of cold fluid is 
Thermal conductivity of cold fluid is 
Prandtl number of cold fluid is 
a.1
Calculate the heat transfer using the overall energy balance on the hot fluid.
Substitute 
for 
,
for 
, 
for 
, and 
for 
.
a.2
Apply energy balance to the cold fluid.
Substitute 
for 
,
for 
,
for 
, 
for 
.
b)
Write the expression for LMTD for counter flow heat exchanger.
Substitute for , for ,
for , and for .
Find the length of the Counter flow heat exchanger using the following relation:
Substitute for ,
for 
,
for 
,
for 
.
Therefore, the total heat transfer is 
.
Therefore the outlet temperature of the cold fluid is 
.
Therefore the length of the heat exchanger is 
.
Add Answer to:
A concentric tube heat exchanger for cooling lubricating oil
is
comprised of a thin-walled inner tube...
A concentric tube heat exchanger for cooling lubricating oil consists of a thin-walled inner tube of...
A concentric tube heat exchanger for cooling lubricating oil
consists of a thin-walled inner tube of 25 mm diameter carrying
water and an outer tube of 45 mm diameter carrying the oil. The
exchanger operates in countercurrent flow with an overall heat
transfer coefficient of 55 W/m2 K and the tabulated average
properties given below. Mass flow rates of oil and water are both
0.1 kg/s, oil enters the exchanger at 100°C, and water enters the
exchanger at 30°C. (a)...
Problem (25 Points - Chapter 11) A concentre tube heat exchanger for cooling lubricating oil is...
Problem (25 Points - Chapter 11) A concentre tube heat exchanger for cooling lubricating oil is comprised of a thin-walled me tube of 25-mm diameter carrying water and an our tube of 45mm diameter coming the The heat exchanger operates in counterflow with an overall heat transfer coefficient of W K and the average property as given in the table below. If the outlet temperature of the oil is 60°C, determine the following (a) total heat transfer rate, (b) outlet...
Twenty [kw] of heat is to be removed from 375 [k] water flowing at 0.15 [kg/s] into the inner pipe of concentric tube heat exchanger. Cooling water enters the annulus at 290 [k] and leaves at 320...
Twenty [kw] of heat is to be removed from 375 [k] water flowing at 0.15 [kg/s] into the inner pipe of concentric tube heat exchanger. Cooling water enters the annulus at 290 [k] and leaves at 320 [k] with a flow in the opposite direction of the inner flow. The diameter of the thin- walled inner pipe is 2.5 [cm] a) b) c) Calculate the exit temperature of the hot fluid and the mass flow rate of the cold fluid...
A concentric tube heat exchanger of length L = 2 m is used to thermally process...
A concentric tube heat exchanger of length L = 2 m is used to thermally process a pharmaceutical product flowing at a mean velocity of u_m,c = 0.1 m/s with an inlet temperature of T_c,i = 20 degree C. The inner tube of diameter D_i = 10 mm is thin walled, and the exterior of the outer tube (D_0 = 20 mm) is well insulated. Water flows in the annular region between the tubes at a mean velocity of u_m,h...
A thin-walled double-pipe counter-flow heat exchanger is to be used to cool oil (cp-2200 /kg K)...
A thin-walled double-pipe counter-flow heat exchanger is to be used to cool oil (cp-2200 /kg K) from 150 C to 40°C at a rate of 2 kg/s by water (c 4180J/kg.K) that enters at 22°C at a rate of 1.5 kg/s. The diameter of the tube is 2.5 cm, O and its length is 6 m. Let the water inlet temperature vary from 5°C to 25°C. Identify the graph that depicts the overall heat transfer coefficient as a function of...
Oil of unknown properties is heated in a shell-and-tube heat exchanger with one shell pass and...
Oil of unknown properties is heated in a shell-and-tube heat exchanger with one shell pass and 20 tube passes. The oil flows through the shell, and hot water flows inside the single copper tube that has an inner diameter of 20 mm, a wall thickness of 2 mm, and a length of 3 m per pass. The water enters at 360 K at a mass flow rate of 0.2 kg/s and leaves at 300 K. The inlet and outlet temperatures...
A counter-flow heat exchanger is stated to have an overall heat transfer coefficient of 284 W/m2.K...
A counter-flow heat exchanger is stated to have an overall heat transfer coefficient of 284 W/m2.K when operating at design and clean conditions. Hot fluid enters the tube side at 101°C and exits at 71°C, while cold fluid enters the shell side at 27°C and exits at 42°C. After a period of use, built-up scale in the heat exchanger gives a fouling factor of 0.0004 m2 K/W. The surface area is 93 m². Assume both hot and cold fluids have...
Two-pipe concentric concentric) for cooling the engine oil with the help of a water stream in...
Two-pipe concentric concentric) for cooling the engine oil with the help of a water stream in a large diesel engine a reverse (opposite) flow heat exchanger is used. Water at a flow rate of 0.3 kg/h from inside pipe with an inside diameter of 56 mm It flows. The inner pipe is made of stainless steel with a heat transmission coefficient of 16 W/mc and is meat (wall its thickness is 3 mm. Apart from this there is another pipe...
A concentric-pipe parallel-flow heat exchanger is to heat water (cp = 4.18 kJ/kg.K) from 20°C to...
A concentric-pipe parallel-flow heat exchanger is to heat water (cp = 4.18 kJ/kg.K) from 20°C to 80°C at a rate of 1.2 kg/s. The heating is to be accomplished by geothermal water (Cp =4.31 kJ/kg.K) available at 160°C at a mass flow rate of 2.0 kg/s. The inner pipe is thin-walled and has a diameter of 1.5 cm. If the overall heat transfer coefficient of the heat exchanger is 640 W/m2.K, determine the length of the pipe required to achieve...
please do 11.33 11.32 A single-pass, cross-flow heat exchanger uses hot exhaust gases (mixed) to heat...
please do 11.33
11.32 A single-pass, cross-flow heat exchanger uses hot exhaust gases (mixed) to heat water (unmixed) from 30 to 80°C at a rate of 3 kg/s. The exhaust gases, hav- ing thermophysical properties similar to air, enter and exit the exchanger at 225 and 100°C, respectively. If the overall heat transfer coefficient is 200 W/m2.K, estimate the required surface area. 11.33 Consider the fluid conditions and overall heat transfer coefficient of Problem 11.32 for a concentric tube heat...
A concentric tube heat exchanger for cooling lubricating oil
consists of a thin-walled inner tube of 25 mm diameter carrying
water and an outer tube of 45 mm diameter carrying the oil. The
exchanger operates in countercurrent flow with an overall heat
transfer coefficient of 55 W/m2 K and the tabulated average
properties given below. Mass flow rates of oil and water are both
0.1 kg/s, oil enters the exchanger at 100°C, and water enters the
exchanger at 30°C. (a)...
Problem (25 Points - Chapter 11) A concentre tube heat exchanger for cooling lubricating oil is comprised of a thin-walled me tube of 25-mm diameter carrying water and an our tube of 45mm diameter coming the The heat exchanger operates in counterflow with an overall heat transfer coefficient of W K and the average property as given in the table below. If the outlet temperature of the oil is 60°C, determine the following (a) total heat transfer rate, (b) outlet...
Twenty [kw] of heat is to be removed from 375 [k] water flowing at 0.15 [kg/s] into the inner pipe of concentric tube heat exchanger. Cooling water enters the annulus at 290 [k] and leaves at 320 [k] with a flow in the opposite direction of the inner flow. The diameter of the thin- walled inner pipe is 2.5 [cm] a) b) c) Calculate the exit temperature of the hot fluid and the mass flow rate of the cold fluid...
A concentric tube heat exchanger of length L = 2 m is used to thermally process a pharmaceutical product flowing at a mean velocity of u_m,c = 0.1 m/s with an inlet temperature of T_c,i = 20 degree C. The inner tube of diameter D_i = 10 mm is thin walled, and the exterior of the outer tube (D_0 = 20 mm) is well insulated. Water flows in the annular region between the tubes at a mean velocity of u_m,h...
A thin-walled double-pipe counter-flow heat exchanger is to be used to cool oil (cp-2200 /kg K) from 150 C to 40°C at a rate of 2 kg/s by water (c 4180J/kg.K) that enters at 22°C at a rate of 1.5 kg/s. The diameter of the tube is 2.5 cm, O and its length is 6 m. Let the water inlet temperature vary from 5°C to 25°C. Identify the graph that depicts the overall heat transfer coefficient as a function of...
Oil of unknown properties is heated in a shell-and-tube heat exchanger with one shell pass and 20 tube passes. The oil flows through the shell, and hot water flows inside the single copper tube that has an inner diameter of 20 mm, a wall thickness of 2 mm, and a length of 3 m per pass. The water enters at 360 K at a mass flow rate of 0.2 kg/s and leaves at 300 K. The inlet and outlet temperatures...
A counter-flow heat exchanger is stated to have an overall heat transfer coefficient of 284 W/m2.K when operating at design and clean conditions. Hot fluid enters the tube side at 101°C and exits at 71°C, while cold fluid enters the shell side at 27°C and exits at 42°C. After a period of use, built-up scale in the heat exchanger gives a fouling factor of 0.0004 m2 K/W. The surface area is 93 m². Assume both hot and cold fluids have...
Two-pipe concentric concentric) for cooling the engine oil with the help of a water stream in a large diesel engine a reverse (opposite) flow heat exchanger is used. Water at a flow rate of 0.3 kg/h from inside pipe with an inside diameter of 56 mm It flows. The inner pipe is made of stainless steel with a heat transmission coefficient of 16 W/mc and is meat (wall its thickness is 3 mm. Apart from this there is another pipe...
A concentric-pipe parallel-flow heat exchanger is to heat water (cp = 4.18 kJ/kg.K) from 20°C to 80°C at a rate of 1.2 kg/s. The heating is to be accomplished by geothermal water (Cp =4.31 kJ/kg.K) available at 160°C at a mass flow rate of 2.0 kg/s. The inner pipe is thin-walled and has a diameter of 1.5 cm. If the overall heat transfer coefficient of the heat exchanger is 640 W/m2.K, determine the length of the pipe required to achieve...
please do 11.33
11.32 A single-pass, cross-flow heat exchanger uses hot exhaust gases (mixed) to heat water (unmixed) from 30 to 80°C at a rate of 3 kg/s. The exhaust gases, hav- ing thermophysical properties similar to air, enter and exit the exchanger at 225 and 100°C, respectively. If the overall heat transfer coefficient is 200 W/m2.K, estimate the required surface area. 11.33 Consider the fluid conditions and overall heat transfer coefficient of Problem 11.32 for a concentric tube heat...
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