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In a certain heat exchanger, cold fluid enters at 40oC and rate of the flow is 1650 kg/hr. The hot fluid is at a temperature of 130oC and cold fluid leaves the heat exchanger at 90oC. Specific heat of the cold fluid is 3.5 kJ/kg-K. If heat transfer area is 0.707 m2, then the overall heat transfer coefficient is
- a)1840 W/m2-K
- b)184 W/m2-K
- c)18.4 W/m2-K
- d)2250 W/m2-K
Correct answer is option 'A'. Can you explain this answer?
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In a certain heat exchanger, cold fluid enters at 40oC and rate of the...
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Heat Exchanger Overview
In this scenario, we're analyzing a heat exchanger involving a cold fluid and a hot fluid. The cold fluid enters at 40°C and exits at 90°C, while the hot fluid enters at 130°C.
Key Data
- Cold fluid inlet temperature (Tci): 40°C
- Cold fluid outlet temperature (Tco): 90°C
- Hot fluid inlet temperature (Thi): 130°C
- Cold fluid flow rate (m): 1650 kg/hr
- Specific heat (Cp) of cold fluid: 3.5 kJ/kg-K
- Heat transfer area (A): 0.707 m²
Heat Transfer Calculation
1. Convert Flow Rate:
Convert the flow rate from kg/hr to kg/s:
1650 kg/hr = 1650 / 3600 = 0.4583 kg/s.
2. Calculate Heat Transfer (Q):
Use the formula:
Q = m * Cp * (Tco - Tci).
Substituting in the values:
Q = 0.4583 kg/s * 3.5 kJ/kg-K * (90 - 40)°C
Q = 0.4583 * 3.5 * 50 = 80.79 kW = 80790 W.
Log Mean Temperature Difference (LMTD)
3. Calculate LMTD:
LMTD = (ΔT1 - ΔT2) / ln(ΔT1 / ΔT2), where:
ΔT1 = Thi - Tco = 130 - 90 = 40°C
ΔT2 = Thi - Tci = 130 - 40 = 90°C
LMTD = (40 - 90) / ln(40 / 90) = -50 / ln(0.444) = 50 / 0.8109 = 61.7°C.
Overall Heat Transfer Coefficient (U)
4. Calculate U using Q = U * A * LMTD:
Rearranging gives:
U = Q / (A * LMTD).
Substituting:
U = 80790 W / (0.707 m² * 61.7°C) = 1840 W/m²-K.
Thus, the overall heat transfer coefficient is 1840 W/m²-K, confirming that option 'A' is indeed correct.
In this scenario, we're analyzing a heat exchanger involving a cold fluid and a hot fluid. The cold fluid enters at 40°C and exits at 90°C, while the hot fluid enters at 130°C.
Key Data
- Cold fluid inlet temperature (Tci): 40°C
- Cold fluid outlet temperature (Tco): 90°C
- Hot fluid inlet temperature (Thi): 130°C
- Cold fluid flow rate (m): 1650 kg/hr
- Specific heat (Cp) of cold fluid: 3.5 kJ/kg-K
- Heat transfer area (A): 0.707 m²
Heat Transfer Calculation
1. Convert Flow Rate:
Convert the flow rate from kg/hr to kg/s:
1650 kg/hr = 1650 / 3600 = 0.4583 kg/s.
2. Calculate Heat Transfer (Q):
Use the formula:
Q = m * Cp * (Tco - Tci).
Substituting in the values:
Q = 0.4583 kg/s * 3.5 kJ/kg-K * (90 - 40)°C
Q = 0.4583 * 3.5 * 50 = 80.79 kW = 80790 W.
Log Mean Temperature Difference (LMTD)
3. Calculate LMTD:
LMTD = (ΔT1 - ΔT2) / ln(ΔT1 / ΔT2), where:
ΔT1 = Thi - Tco = 130 - 90 = 40°C
ΔT2 = Thi - Tci = 130 - 40 = 90°C
LMTD = (40 - 90) / ln(40 / 90) = -50 / ln(0.444) = 50 / 0.8109 = 61.7°C.
Overall Heat Transfer Coefficient (U)
4. Calculate U using Q = U * A * LMTD:
Rearranging gives:
U = Q / (A * LMTD).
Substituting:
U = 80790 W / (0.707 m² * 61.7°C) = 1840 W/m²-K.
Thus, the overall heat transfer coefficient is 1840 W/m²-K, confirming that option 'A' is indeed correct.
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In a certain heat exchanger, cold fluid enters at 40oC and rate of the flow is 1650 kg/hr. The hot fluid is at a temperature of 130oC and cold fluid leaves the heat exchanger at 90oC. Specific heat of the cold fluid is 3.5 kJ/kg-K. If heat transfer area is 0.707 m2, then the overall heat transfer coefficient isa)1840 W/m2-Kb)184 W/m2-Kc)18.4 W/m2-Kd)2250 W/m2-KCorrect answer is option 'A'. Can you explain this answer?
Question Description
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In a certain heat exchanger, cold fluid enters at 40oC and rate of the flow is 1650 kg/hr. The hot fluid is at a temperature of 130oC and cold fluid leaves the heat exchanger at 90oC. Specific heat of the cold fluid is 3.5 kJ/kg-K. If heat transfer area is 0.707 m2, then the overall heat transfer coefficient isa)1840 W/m2-Kb)184 W/m2-Kc)18.4 W/m2-Kd)2250 W/m2-KCorrect answer is option 'A'. Can you explain this answer? for GATE 2024 is part of GATE preparation. The Question and answers have been prepared according to the GATE exam syllabus. Information about In a certain heat exchanger, cold fluid enters at 40oC and rate of the flow is 1650 kg/hr. The hot fluid is at a temperature of 130oC and cold fluid leaves the heat exchanger at 90oC. Specific heat of the cold fluid is 3.5 kJ/kg-K. If heat transfer area is 0.707 m2, then the overall heat transfer coefficient isa)1840 W/m2-Kb)184 W/m2-Kc)18.4 W/m2-Kd)2250 W/m2-KCorrect answer is option 'A'. Can you explain this answer? covers all topics & solutions for GATE 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for In a certain heat exchanger, cold fluid enters at 40oC and rate of the flow is 1650 kg/hr. The hot fluid is at a temperature of 130oC and cold fluid leaves the heat exchanger at 90oC. Specific heat of the cold fluid is 3.5 kJ/kg-K. If heat transfer area is 0.707 m2, then the overall heat transfer coefficient isa)1840 W/m2-Kb)184 W/m2-Kc)18.4 W/m2-Kd)2250 W/m2-KCorrect answer is option 'A'. Can you explain this answer?.
Solutions for In a certain heat exchanger, cold fluid enters at 40oC and rate of the flow is 1650 kg/hr. The hot fluid is at a temperature of 130oC and cold fluid leaves the heat exchanger at 90oC. Specific heat of the cold fluid is 3.5 kJ/kg-K. If heat transfer area is 0.707 m2, then the overall heat transfer coefficient isa)1840 W/m2-Kb)184 W/m2-Kc)18.4 W/m2-Kd)2250 W/m2-KCorrect answer is option 'A'. Can you explain this answer? in English & in Hindi are available as part of our courses for GATE.
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