Condenser Thermal Design:: Solved Examples

Problem.1

28000 kg/hr of pure ethyl alcohol at 2 psi is to be condensed by water from 85 degree F to 120.
A dirt factor of 0.003 should be provided. A pressure drop at 2 psi is allowable for vapour and 10 psi for the water. Calculate the required size of a 1-2 horizontal condenser using 1 inch OD, 14 BWG, Tubes 16 ft long on 1 1/4 inch triangular pitch.

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Problem.2

30000 kg/hr of pure ethyl alcohol at 2 psi is to be condensed by water from 85 degree F to 125 Degree F. A dirt factor of 0.004 should be provided. A pressure drop at 2 psi is allowable for the vapour and 10 psi for the water.

Calculate the required size of 1-2 horizontal condenser using 1 inch OD 14 BWG, tubes 16 ft long on 1 1/4 inch triangular pitch.

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Problem.3

A horizontal 1-2 condenser is required for the condenser of 27200 kg/hr of substantially pure n-propyl alcohol coming from top of distilling column operating at 15 psig at which pressure it boils at 118 Degree C. Water at 29.5 degree C will be used as the cooling medium. A dirt factor of 0.003 is required with allowable pressure drops of 2.0 psi for the vapour pressure and 10 psi for the water.

Assume that 8 ft tubes are used. Tubes are to be 3/4 Inch OD. 16 BWG on 15/16 Inch triangular pitch. Assume fan tube passes and the maximum baffle spacing. Design the condenser.

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Rotary Drier Design Example

Problem.1 

A rotary drier using counter-current flow is to be used to dry 12000 kg/hr of wet salt containing 5% water (wet basis). Heated air at 147 Degree C with 50 Degree C wet bulb temp is available. The specific heat of the salt is 0.21. The outlet temp of air and salt are 72 degree C and 93 degree C respectively. Calculate the length and diameter of the drier required.

DATA::

Humidity of entering air = 0.05 kg water/kg dry air
Mass velocity of air = 5000 kg/hr-m2
Spe. Heat of salt = 0.21 kcal/kg. C

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Routh Problem 6 Solution Page

Routh Stability Test :: Solved Examples

Problem.01.

Examine the stability of the characteristics equation :

s⁵ + 2 s⁴ +4 s³ +8 s² +3 s + 1 = 0

using routh's criteria.

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Problem.02.

For the system given Below write down the characterictics equation with the help of the routh test, comment on the stability for kc = 4  . Also find the value of kc for which the system is unstable

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Problem.03.

The open loop transfer function of the control system is given as ::

           G(s) =    K_c(s + 1)      

                     S (s + 2) (s + 3)

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Problem.04.

By the means of Routh test determine the stability of the system when kc = 2.0

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Problem.05.

For the control system in Fig, determine the value of K above which the system is unstable.

Determine the value of K for which two of the roots are on the imaginery axis and determine the values of these imaginery roots and the remaining roots.

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Problem.06.

A control system is represented by the means of a block diagram as shown in the fig.

Comment on the stability of the system.

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Problem.07.

Consider the following feedback control system and make stability analysis with routh criterion, Find the critical stability conditions when Ţ_{i  = 0.1}

S³ + 2 s ²(2 + K_c) s + K_c/Ţ_i = 0

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