Aheat exchanger is to be constructed by forming copper tubing into a coil and placing the latter inside an insulated steel shell. in this exchanger, water will flow inside the tubing, and a hydrocarbon vapor at a rate of 0.126 kg/s will be condensing on the outside surface of the tubing. the inside and outside diameters of the tube are 0.0127 and 0.0152 m, respectively, inlet and exit temperatures for the water are 10 and 32°c, respectively. the heat of conden- sation of the hydrocarbon at a condensing temperature of 88°c is 335 kj/kg, and the heat- transfer coefficient for the condensing vapor is 1420 w/m².k. heat losses from the shell may be neglected. what length of copper tubing will be required to accomplish the desired heat transfer?

Explanation:

The given data is as follows.

Flow of mass rate of hydrocarbon, m = 0.126 kg/s

Heat of condensation, () = 335 kJ/kg

For water , and

Formula for transfer of heat is as follows.

                      Q =

                          =

                           = 41.875 kJ/s

Also, it is known that Q =

As it is given that for condensing T = .

        =      

                             =

                             =

                             =

As it is given that inside and outside diameters of the tube are as follows.

                = 0.0127, and = 0.0152 m

Formula for A =  ......... (1)

Hence, putting value of equation (1) in the following formula.

              Q =

     41.875 kJ/s =

                L = \frac{41.875 \times 1000 J/s}{743.17 W^{o}C}

                    = 56.34 h

Thus, we can conclude that length of copper tubing will be required to accomplish the desired heat transfer 56.34 h.

The answer to your question is below

Explanation:

Noble gases has  their levels of energy completed so they can not react with another element, they can not interchange electrons .

           electronic configuration

He               1 s ²

Ne               1s² 2s² 2p⁶

Ar                 [Ne] 3s² 3p⁶

Kr                 [Ar] 3d¹⁰ 4s² 4p⁶

Xe                [Kr] 4d¹⁰ 5s² 5p⁶

Rn                [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁶

In the electronic configurations we can see that Noble gases have 8 electrons in their outermost shell, so they do not need to react to be stable, they are stable.