Researches On Flow Resistance Characteristics Of Tube In Liquid-phase Organic Heat Transfer Material Heaters

So far, hydrodynamic computation for organic heat transfer material heater can only rely on experience in practice and reference of hydrodynamic computation for hot-water boiler, which restricted the development and design of organic heat transfer material heater and its engineering application. So, it is significant to research on flow resistance characteristics of heating surface in organic heat transfer material heater. Helical coil in organic heat transfer material heater is selected as research subject. The paper researches flow resistance characteristics of heat transfer fluid THERMINOL®66 in helical coil, using the method of numerical simulation and theoretical research. the main conclusions are as follows:(1) Geometric parameter of helical coil has much greater impact on flow resistance characteristics. Unit length pressure loss decreases with the increases of pipe diameter and coil diameter, and increases with the increases of pitch. General friction factor decreases first and then increases with the increases of pipe diameter, decreases with the increases of coil diameter, and increases with the increases of pitch.(2) Unit length pressure loss increases and friction factor decreases with the increases of velocity, when heat transfer fluid THERMINOL®66 flows in helical coil.(3) Flow resistance characteristics of heat transfer fluid THERMINOL®66 are different from water’s when they flow in helical coil, because heat transfer fluid THERMINOL®66 has its own unique thermal properties. Temperature has a negative impact on flow resistance when heat transfer fluid THERMINOL®66 flows in helical coil, while temperature has few impacts on flow resistance when water flows in helical coil. The trend of unit length pressure loss and general friction factor with temperature and viscosity with temperature is accordant. They decrease with the increases of temperature.(4) Flow resistance of heat transfer fluid THERMINOL®66 in helical coil is more complicated and even bigger than that in straight pipe, due to the unique geometric characteristics of helical coil. Flow resistance of heat transfer fluid THERMINOL®66 in helical coil is 1.47 times than in straight pipe. General friction factor of heat transfer fluid THERMINOL®66 in helical coil is 1.66 times than that in straight pipe.(5) When heat transfer fluid THERMINOL®66 flows in helical coil, five main factors, coil diameter, pipe diameter, pitch, victory and viscosity, in the impact of general friction factor are analyzed by using multiple factor analysis: coil diameter > pipe diameter > pitch> viscosity > victory.(6) General friction factor formula is developed on the basis of dimensionless numbers—Reynolds number(Dean number),d/D and l/d, when heat transfer fluid THERMINOL®66 is turbulent flow in helical coil. The numerical simulation condition: 200mm<D<700mm, 8mm<d<48mm, 40mm<l<240mm, 1.25m/s<u<3m/s, 5.760mm2/s<υ<0.935 mm2/s, accordingly, 17105<Re<103040, 0.04<d/D<0.24, 1.25<l/d<10.(7) These dimensionless numbers change regarding the general friction factor impacts that are simulated: Re>d/D>l/D. And they have a great influence on general friction factor.