Twente mass and heat transfer water tunnel: Temperature controlled turbulent multiphase channel flow with heat and mass transfer.

A new vertical water tunnel with global temperature control and the possibility for bubble and local heat and mass injection has been designed and constructed. The new facility offers the possibility to accurately study heat and mass transfer in turbulent multiphase flow (gas volume fraction up to 8%) with a Reynolds-number range from 1.5 × 104 to 3 × 105 in the case of water at room temperature. The tunnel is made of high-grade stainless steel permitting the use of salt solutions in excess of 15% mass fraction. The tunnel has a volume of 300 l. The tunnel has three interchangeable measurement sections of 1 m height but with different cross sections (0.3 × 0.04 m2, 0.3 × 0.06 m2, and 0.3 × 0.08 m2). The glass vertical measurement sections allow for optical access to the flow, enabling techniques such as laser Doppler anemometry, particle image velocimetry, particle tracking velocimetry, and laser-induced fluorescent imaging. Local sensors can be introduced from the top and can be traversed using a built-in traverse system, allowing, for example, local temperature, hot-wire, or local phase measurements. Combined with simultaneous velocity measurements, the local heat flux in single phase and two phase turbulent flows can thus be studied quantitatively and precisely.

The boiling Twente Taylor-Couette (BTTC) facility: Temperature controlled turbulent flow between independently rotating, coaxial cylinders.

A new Taylor-Couette system has been designed and constructed with precise temperature control. Two concentric independently rotating cylinders are able to rotate at maximum rates of f(i) = ± 20 Hz for the inner cylinder and f(o) = ± 10 Hz for the outer cylinder. The inner cylinder has an outside radius of r(i) = 75 mm, and the outer cylinder has an inside radius of r(o) = 105 mm, resulting in a gap of d = 30 mm. The height of the gap is L = 549 mm, giving a volume of V = 9.3 L. The geometric parameters are η = r(i)/r(o) = 0.714 and Γ = L/d = 18.3. With water as working fluid at room temperature, the Reynolds numbers that can be achieved are Re(i) = ω(i)r(i)(r(o) - r(i))/ν = 2.8 × 10(5) and Re(o) = ω(o)r(o)(r(o) - r(i))/ν = 2 × 10(5) or a combined Reynolds number of up to Re = (ω(i)r(i) - ω(o)r(o))(r(o) - r(i))/ν = 4.8 × 10(5). If the working fluid is changed to the fluorinated liquid FC-3284 with kinematic viscosity 0.42 cSt, the combined Reynolds number can reach Re = 1.1 × 10(6). The apparatus features precise temperature control of the outer and inner cylinders separately and is fully optically accessible from the side and top. The new facility offers the possibility to accurately study the process of boiling inside a turbulent flow and its effect on the flow.