题目内容

Which of the following is not an effective measure to enhance heat transfer?

A. Corrugated tube
B. Micro-fins
C. Smooth tube
Dimpled turfaces

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The hot fluid A is used to heat oil in a heat exchanger. The inlet and outlet temperature for A is 300℃ and 200℃, and the oil is heated from 25℃ to 175℃, so the downstream logarithmic mean temperature difference of the two fluid is ?

A. 104.2 ℃
B. 148.5 ℃
C. 130 ℃
D. 175 ℃

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The hot fluid A is used to heat oil in a heat exchanger. The inlet and outlet temperature for A is 300℃ and 200℃, and the oil is heated from 25℃ to 175℃, so the upstream logarithmic mean temperature difference of the two fluid is ?

A. 104.2 ℃
B. 148.5 ℃
C. 130 ℃
D. 175 ℃

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A double-pipe heat exchanger is used to cool oil. Cold water flows through the small pipe, while oil flows through the outside of the samll pipe. The oil is cooled from 107℃ to 32℃, while the water is heated from 17℃ to 60℃, so the logarithmic mean temperature difference is?

A. 28.2 ℃
B. 48.5 ℃
C. 51.2 ℃
D. 23.4 ℃

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The temperature correction factor is determined by the dimensionless factors P and R, what is the physical meaning of P?

A. The ratio of the actual temperature rise of the cold fluid and the maximum temperature rise that can be achieved theoretically
B. The ratio of the thermal capacity of the clod and hot fluid
C. The ratio of the actual temperature drop of the hot fluid and the maximum temperature drop that can be achieved theoretically
Do not have physical meaning

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Which of the following is not an effective measure to enhance heat transfer?

A. Corrugated tube B. Micro-fins C. Smooth tube Dimpled turfaces

The hot fluid A is used to heat oil in a heat exchanger. The inlet and outlet temperature for A is 300℃ and 200℃, and the oil is heated from 25℃ to 175℃, so the downstream logarithmic mean temperature difference of the two fluid is ?

The hot fluid A is used to heat oil in a heat exchanger. The inlet and outlet temperature for A is 300℃ and 200℃, and the oil is heated from 25℃ to 175℃, so the upstream logarithmic mean temperature difference of the two fluid is ?

A double-pipe heat exchanger is used to cool oil. Cold water flows through the small pipe, while oil flows through the outside of the samll pipe. The oil is cooled from 107℃ to 32℃, while the water is heated from 17℃ to 60℃, so the logarithmic mean temperature difference is?

The temperature correction factor is determined by the dimensionless factors P and R, what is the physical meaning of P?

A. Corrugated tube
B. Micro-fins
C. Smooth tube
Dimpled turfaces