I need p, u, Cp, and k. Water at 20 C with a mass flow rate of 1.0 kg/s enters a

Question

I need p, u, Cp, and k. Water at 20 C with a mass flow rate of 1.0 kg/s enters an annulus formed by an inner pipe having an OD of 2.5 cm and an outer pipe having an ID of 10 cm The wall temperature of the inner pipe varies from 80 C at the inlet to 100 C at the outlet. The outer surface of the outer pipe is well insulated. Calculate the length of the annulus required to heat the water to 75 C Table A.7 Properties of Liquid Water at Saturation Pressure: SI Units 273 0 999.9 0.7 4226 1.789 13.7_ 283 10 999.7 288 15 999.1 1.300 9.5 0.551 0.141 1136 20 9982 2 182 303 30 95.7 3o 4176 308 35 994.1 313 40 9922 318 45 990.2 0.658 4.3 8.833 157 555.1 0.556 3.55 14.59 348 75 974.9 373 100 9584 171 235.4 0.172 201.0 0.244 143 140.0 212 123 2117 191 110 290.3 173 1.01 396.5 0.160 0.95 5172 413 140 9263 433 160 907.6 108 4285 453 180 886.6 12.1 4396 473 200 8628 13.5 4501 493 220 837.0 152 4605 513 240 809.0 172 4731 533 260 779.0 20.0 4982 553 280 750.0 23.8 5234 573 300 712.5 29.5 5694 0.173 171.6 0.170 139.3 162 113.8 149 0.90 6714 141 086 848.5 0.135 0.86 1076 .131 0.89 1360 0.128 0.98 1766 0.132 92.18 Source: Refs.111 and 13

Explanation / Answer

In such cases, you have to take the average values of the properties at inlet and outlet temperatures.

So density= (998.2 + 974.9)/2 = 986.55 kg/m3.

Cp = (4182+4190)/2 = 4186 J/kg.K

k = (0.597+ 0.671)/2 = 0.634 W/m.K

I didn't understand, what do you mean by u? Is it viscosity , velocity or overall heat transfer coefficient. Comment below I will answer it

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