For outlet temperature calculations. Nonetheless, neither ε-Ntu or LMTD approaches can address the heat transfer / pumping power tradeoffs, which is the crux of a balanced heat exchanger design. For this purpose, Bejan (1987) established the thermodynamic design.
Thermal design calculations of Shell & Tube condensers for horizontal condensers, vertical condensers including reflux condensers; main features: +Support S.I Units/English (U.S) Units of measurement, Units converter containing 23 measurements and 200 units. +Import physical properties data to hot side and cold side from Microsoft Excel & from WeBBusterZ Physical properties database (included. The condenser, coupled with the corresponding fan, and characterized by four rows of finned tubes while the third one refers to a condenser composed of 21 modules (18 parallel-flow and 3 dephlegmator) with three tubes rows. The first step of the analysis has been the design calculation of the condenser main. Calculation; we can ignore this in our calculations since we consider the overall air-side resistance to be constant for all of our calculations). The resistance of the heat exchanger tube is a function of the thickness of the tube s, the conductivity of the tube k, and the mean cross 2.
A surface condenser is required to deal with 15 000 kg/h wet steam. Wet steamtemperature is 37 C and enters the condenser with 0.95 quality (dryness fractionis 0.95). The water used for cooling has the following data:
- Inlet pressure 1.20 bar, inlet temperature 7 C
- Outlet pressure 1.013 bar, outlet temperature 22 C
Calculate the flow rate of cooling water and tube surface of the condenser.Assume that the cooling water velocity through tubes is 1.5 m/sInputs | Units | |
Wet steam inlet temperature | 37 | C |
Steam quality | 0,95 | . |
Cooling water inlet temperature | 7 | C |
Cooling water inlet pressure | 1,2 | bar |
Cooling water outlet temperature | 22 | C |
Cooling water outlet pressure | 1,013 | bar |
Steam mass flow | 15000 | kg/h |
Cooling water speed | 1,5 | m/s |
Outputs | . | . |
Wet steam pressure | 0,06274 | bar |
Enthalpy of steam at inlet | 2448,28 | kJ/kg |
Entropy of condense | 154,92 | kJ/kg |
Rejected heat/hour | 34400441,72 | kJ/h |
Rejected heat/second | 9555,68 | kJ/s = kW |
Enthalpy of water at inlet | 29,53 | kJ/kg |
Enthalpy of water at outlet | 92,31 | kJ/kg |
Water mass flow | 547885,14 | kg/h |
The overall heat transfer coefficient can be calculated according to BEAMAor HEI standards.
BEAMA: British Electrical and Allied Manufacturers Association
BEAMA publication on the recommended practice for design of surface typesteam condenser
HEI: Heat Exchanger Institute
HEI standards for steam surface condensers
Outputs | Unit | |
Heat transfer coeff.(BEAMA) | 2,95235 | KW/m2,K |
Logarithmic mean temp. diff. | 49,83 | degree K |
Required area | 64,96 | m2 |
Outputs | Unit | |
Heat transfer coeff.(HEI) | 3,60991 | kW/m2,K |
Required area | 53,12 | m2 |