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

本工作主要使用d=6 mm和L=60 mm(L/d=10)的铜镍(Cu-Ni30%)管。它测量了内表面粗糙度(Ra)为0.15μm。在固定的ΔT^SUB^Out和Δ^TSUB</sup>和ⁱⁿ时，CHF随流速的增加而增大。这说明了CHF随出口和进口过冷度的增加而变化的趋势。ΔT^SUB和Δ^T^In>大于约30 K和40 K增量…的CHFΔT_&lt；Sub，Out&>和ΔT_&lt；Sub，In&gt；分别增加，更加轻松。较高的ΔT；SUB，OUT&gT；和ΔT_&L；SUB，IN&gT；的增长率变低。等式给出的曲线。(1)和(2)在每个流速下均为compared.Bo=0.082{d/√&lt；σ/g(ρ_l-ρ_g)&gt；}^&lt；-0.1&gt；(L)^-0.1；Sc^&lt；0.7&gt；(1)、Bo=C_1{d/√&lt；σ/g(ρ_l-ρ_g)&gt；}^&lt；-0.1&gt；ΔT_t；SUB，OUT&gT；[大于或等于]30K和ΔT_&lt；SUB，IN&gT；[大于或等于]40K的CHF数据与出口和进口过冷度EQs关联式给出的值符合得很好。(1)和(2)。在低热流速度和高热流速度下，管材对热膨胀系数的影响不大，但CuPro-Ni30%的导热系数λ是SUS304的2.1倍。根据这一事实，假设了出口和进口过冷度EQs的相关性。(1)和(2)不会受到管材差异的影响。较少

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