PERFORMANCE IMPROVEMENT OF DOUBLE PIPE HEAT EXCHANGER BY USING TURBULATOR
The various techniques for achieving improved heat transfer are usually referred to as “heat transfer augmentation” or “heat transfer enhancement” and the heat exchanger provided with heat transfer enhancement techniques as “Augmented Heat Exchanger”. The objective is to reduce as many of the factors as possible: Capital Cost, Power Cost, Maintenance Cost, Space and Weight, Consistent with safety and reliability. Present work describes the principal techniques of industrial importance for the augmentation of single phase heat transfer on the inside of tubes namely twisted tapes. So twisted tape should be used in heat exchanger when high heat transfer rate is required and pressure drop is of no significance.
Heat transfer and pressure drop in the horizontal double pipes with and without twisted tape insert
Abstract The heat transfer characteristics and the pressure drop in the horizontal double pipes with twisted tape insert are investigated. Two test sections with different relative pitches are tested. The inner and outer diameters of the inner tube are 8.10 and 9.54 mm, respectively. The twisted tape is made from the aluminium strip with thickness of 1 mm and the length of 2000 mm. Cold and hot water are used as working fluids in shell side and tube side, respectively. The test runs are done at the cold and hot water mass flow rates ranging between 0.01 and 0.07 kg/s, and between 0.04 and 0.08 kg/s, respectively. The inlet cold and hot water temperatures are between 15 and 20 °C, and between 40 and 45 °C, respectively. The results obtained from the tube with twisted insert are compared with those without twisted tape. Non-isothermal correlations based on the data gathered during this work for predicting the heat transfer coefficient and friction factor of the horizontal pipe with twisted taped insert are proposed. The majority of the data falls within ± 15%, ± 10% of the proposed correlations for heat transfer coefficient and friction factor, respectively.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.