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Fouling mitigation
Test Condition : Cooling Water at 5 ft / second . (. 750 OD tubing )
Smooth Bore NEOTISS Microfin ID
Heat Transfer Relative enhancement factor
1.0 1.8
Pressure Drop 1.0 1.6 Table 5 . NEOTISS Microfin ID : relative performance factors .
natural gas combined cycle unit with a capacity of 900 MW and a heat rate of 7,000 BTU / kWh at four operating modes : 1 . Winter conditions ; full pressure 2 . Winter conditions ; 2-on-1 minimum load 3 . Summer conditions ; full pressure 4 . Summer conditions ; 2-on-1 minimum load
A condenser heat transfer improvement was calculated for each operating mode , and an annualized heat rate improvement was calculated by assuming that the plant operated in each mode 25 % of the year . These results are shown in Tables 3 and 4 , respectively .
Performance comparison Smooth Bore vs Microfin ID Neotiss has conducted performance tests to validate the heat transfer and pressure drop gains relative to smooth bore tubing in cooling water . The results shown below confirm up to 80 % heat transfer increase over smooth bore and 60 % increase in pressure drop . The ID surface area increase is 15 %, and therefore most of the performance benefit is coming from the increased turbulation of the water .
Additional tests planned Additional tests are currently underway to compare the fouling rates of smooth vs Microfin ID in a seawater biofouling environment . The effectiveness of various online cleaning systems with various types of ID enhanced tubes will also be evaluated .
Cleaning and maintenance Based on interviews with companies that service commercial water chillers ( where over 90 % of the tubes have internal fins ), they report that cleaning methods are basically the same as with smooth bore , with exception that there are special brush designs to better fit into spiral grooves and these are sold by the companies who manufacture heat exchanger cleaning systems and tools . They further note that frequency of cleaning is important for both smooth and enhanced tubes in order to prevent any scale build up . Once the scale hardens then a chemical cleaning is needed to descale before the brush cleaning