Condensate or Duplex Heater (Liquid- Liquid Heater) Design Calculation formulas with online calculation sheet
- 1 Condensate or Duplex Heater (Liquid- Liquid Heater) Design Calculation formulas with online calculation sheet
- 1.1 Required data for calculation heating surface of Liquid Liquid heater:
- 1.2 Steps in Calculation of heating surface for Liquid Liquid heater:
• According to the in the energy conservation point of view Sugar process industry used liquid liquid heaters for raw juice heating . It is also called condensate heater or duplex heater( for specific design).
• In liquid- liquid heater raw juice heated with process condensate water and It having two types of designs.
- One is normal multi passes arranged in single tube plate design and it located horizontally or vertically. Generally for condensate heaters have located in horizontal position because in the horizontal position heat transfer coefficient having high and also in this design will get proper baffle plate arrangement to the passing of hot fluid(Condensate).
- Another design is called Duplex heater. In this type design will get maximum heat transfer coefficient upto 1200±50 Kcal/m2/hr/oC. When compare to another liquid liquid heater design its having higher heat transfer value , because the passing of hot and cooled fluid is perfectly in counter current direction from entry to leave the heater. Another advantage is high flexibility to proved spare heater or expansion the capacity of heater. In Duplex heater also flexible to collect the condensate (heating media) in different stages as per our process requirement.(i. e as per our required temperature we will get condense in middle stage of heater).
- In sugar process industry while using vapour or steam as a heating media than formulas used for heat transfer coefficient and for evaluate heating surface used . But in condensate heater calculation both are not applicable.
- In this article explain about condensate heater heating surface calculation and for heat transfer coefficient calculation will published in another article.
Required data for calculation heating surface of Liquid Liquid heater:
- Crushing rate = M in T/hr
- Juice % cane = P
- Velocity of Juice = Vj in m/sec
- Juice inlet temperature = ti in oC.
- Condensate Inlet temperature = Ti in oC.
- Condensate Outlet temperature requirement =To in oC.
- Specific heat of juice = Cp in Kal/Kg
- Legment = Lg in mm (Generally Legment taken for Juice heater 12mm, and for evaporators will take 10mm)
- Tube OD = OD in mm
- Tube Thickness = Tk in mm
- Tube length = L in mm
- Tube plate thickness = Tp in mm
- Total Quantity of Condensate water percent on Mixed Juice = W
- Heat transfer coefficient = K in Kcal/m2/hr/oC. (Note : For Dulex Heater this value lies 1200±50 and for Normal condensate heater with proper baffle plate arrangement lies 1000±50 Kcal/m2/hr/oC)
- Proportional factor = β in mm
Steps in Calculation of heating surface for Liquid Liquid heater:
Quantity of juice to be heating = Q =M x P/100 in T/hr
Quantity of heating media (Condensate) = Q xW/100 in T/hr
Fundamental formula :
- Heat received by one = Heat rejected by another.
- M x Cp x (to – ti) = Q x Cw x (To- Ti) Note : Here Cw = specific heat of heating media, for condensate it will take value 1)
- Juice outlet temperature = to ( From the above formula it can be find out the final juice outlet temperature)
Heating Surface :
- For heating surface calculation M x Cp x ΔT = S x K x ∆Tm
- Heating Surface =S = [Q x Cp x ∆T]/ [ K x ∆Tm]
- Here ∆Tm called as logarithmic mean temperature
- ∆T = to-ti
- ∆Ti = Ti-to
- ∆Te = To-ti
Number of tubes per pass & Number of passes:
- (Note :while calculating the area of tube take mean dia of tube i.e Tube OD – Tube Thickness)
- No. of tubes Requirement = N = S/ [π x Mean dia of tube x Tube effective length]
- Number of passes = n = N / number of tubes per pass
In design point of view number of passes always should be even. According to this principle we consider the passes in even number. After the above consideration again calculates the actual heating surface and velocity of juice, it may be differ from required heating surface.
Pressure Drop and Tube Plate area calculation:
Pressure drop across the juice heater
Here pressure drop in MWC , n = number passes , U = actual velocity of juice (after considering the even passes), L = Length of the tube, D = ID of the tube (Note : L & D to be take same units)
Tube Plate Area
- Tube Pitch (P ) = OD of the tube +Legment of the tube + tube clearance+hole clearance
- Proportional factor(β) = Generally β value taken for multiple pass(i.e Juice heaters) 0.6 to 0.8 and for single pass(l.e evaporators or single pass duplex heater) 8 to 1.0.
- Number of tubes will take as per the type of the heater. Suppose
For multi pass heater no. of tubes = Total number of tubes and
For Duplex having two pass in each section than no. of tubes = No. of tubes per pass x 2
For Duplex having single pass in each section than no. of tubes = No. of tubes per pass
(Note :Generally take extra dia in percentage on area occupied for tubes in tube plate for partition plates arrangement, free withdrawal of condensate and noxious gases removal purpose. Its value lies in the range 10 to 20% on area occupied for tubes.)
Heating media (Condensate water) inlet and out line dia :
- Both inlet and outlet will take same dia meter.
- Area required for condensate water entry (m2) =Quantity of heating media ( Q ) in M3/sec / Velocity of Condensate water in m/sec. (Note : Velocity of condensate will take 1.8 to 2.0 m/sec while coming from the pump )
- Dia of the condensate water in mtr = SQRT [ (Area required for condensate water in m2 x (4/π ) ]
Remaining all design parameter can be calculated as same as the normal juice heater calculation.
Fundamental theory of Overall Heat Transfer Coefficient (OHTC)
How to find Condensate Juice Heater Heat Transfer Coefficient Calculation
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