Study on Subcooled Flow Boiling Critical Heat Flux in a Vertical Copper Tube Controlled Dissolved Gas Concentration

1.通过安装在稳压器上的实验水回路，系统地测量了流速（u=4.0 ~ 13.3 m/s）、出口过冷（ΔT_<sub,out> =46 ~ 119k）、进口过冷（ΔT_<sub,in>=68 ~ 148k）和出口压力（P_<out> ~ 800kpa）的过冷流沸腾CHF。本工作主要采用d= 6mm， L= 60mm （L/d=10）的铜镍（Cu-Ni30%）管。测得内表面粗糙度（Ra）为0.15 μm。CHF, q_<cr,sub>,（35点）与测量的出口和进口过冷量，ΔT_<sub,out>和ΔT_<sub,in>，以流速为参数。在固定的ΔT_<sub,out> andΔT_<sub,in>处，CHF随着流速的增加而增大。这些说明了CHF随出口和进口过冷量的增加而变化的趋势。在>中，ΔT_<sub、out>和ΔT_<sub的CHF分别大于30 K和40 K左右，而在>中，ΔT_<sub、out>和ΔT_<sub的CHF分别增大。高ΔT_<sub,out>和ΔT_<sub,in>，增加速率变低。方程给出的曲线。(1)和(2)在每个流速compared.Bo = 0.082 {d /√<σ/ g(ρ_l -ρ_g) >} ^ < -0.1 >我们^ < -0.3 > (L / d) ^ < -0.1 > Sc ^ < 0.7 >(1),博= c₁{d /√<σ/ g(ρ_l -ρ_g) >} ^ < -0.1 >我们——^ < 0.3 > (L / d) ^ < -0.1 > e ^ < - (L / d) / C_2Re ^ < 0.4 > > Sc ^ < * C_3 > > (2), c₁= 0.082,c₂= 0.53和C_3 = 0.7 L / d【小于或等于】大约40 c₁= 0.092,c₂= 0.85和C_3 = 0.9 L / d > 40岁左右。ΔT_<sub,out>【大于或等于】30k和ΔT_<sub,in>【大于或等于】40k的CHF数据与出口过冷和进口过冷的相关性给出的值很好地吻合，式。(1)、(2)。当热流速度高或低时，管材对CHF的影响不大，而Cu-Ni30%的导热系数λ是SUS304的2.1倍。从这一事实可以假设，出口和进口过冷的相关性，公式。(1)和(2)不受管材差异的影响。少

1.Subcooled Flow Boiling Critical Heat Flux in a Vertical Copper Tube Controlled Dissolved Gas ConcentrationThe subcooled flow boiling CHF for the flow velocities (u=4.0 to 13.3 m/s), the outlet subcooling (ΔT_<sub,out> =46 to 119 K), the inlet subcooling (ΔT_<sub,in>=68 to 148 K) and the outlet pressure (P_<out>-800 kPa) are systematically measured by the experimental water loop installed the pressurizer. The Cupro-Nickel (Cu-Ni30%) tube of d=6 mm and L=60 mm (L/d=10) are mainly used in this work. It measures 0.15 μm in the inner surface roughness (Ra). The CHF, q_<cr,sub>, (35 points) are shown versus the outlet and inlet subcoolings measured, ΔT_<sub,out> and ΔT_<sub,in>, with the flow velocity as a parameter. The CHF become higher with an increase in flow velocity at a fixed ΔT_<sub,out> andΔT_<sub,in>. These illustrate the trends in the variation of CHF with increasing outlet and inlet subcoolings. The CHF for the ΔT_<sub,out> and ΔT_<sub,in> greater than around 30 K and 40 K incr … More ease with an increase in ΔT_<sub,out> and ΔT_<sub,in> respectively. The increasing rate becomes lower for higher ΔT_<sub,out> and ΔT_<sub,in>. The curves given by Eqs. (1) and (2) at each flow velocity are compared.Bo=0.082{d/√<σ/g(ρ_l-ρ_g)>}^<-0.1> We^<-0.3>(L/d)^<-0.1> Sc^<0.7>(1)、Bo=C_1{d/√<σ/g(ρ_l-ρ_g)>}^<-0.1> We-^<0.3>(L/d)^<-0.1>e^<-(L/d)/C_2Re^<0.4>> Sc^<*C_3>>(2)where, C_1=0.082, C_2=0.53 and C_3=0.7 for L/d 【less than or equal】 around 40 and C_1=0.092, C_2=0.85 and C_3=0.9 for L/d>around 40. The CHF data for ΔT_<sub,out>【greater than or equal】30 K and ΔT_<sub,in>【greater than or equal】40 K are in good agreement with the values given by the correlation against outlet and inlet subcooling, Eqs. (1) and (2). Little effect of tube material on CHF can be seen for low and high heat flow velocities, although the thermal conductivity, λ, of the Cupro-Nickel (Cu-Ni30%) becomes 2.1 times as large as that of SUS304 one. It is assumed from this fact that the correlations against outlet and inlet subcooling, Eqs. (1) and (2) would not be affected by the difference in tube material. Less