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

1.垂直铜管内溶解气体浓度控制下的过冷沸腾临界热流密度利用安装在加压器上的实验水环系统测量了流速（u=4.0 ~ 13.3 m/s）、出口过冷度（Δ Tsub，out&gt; =46 ~ 119 K）、入口过冷度（Δ Tsub，in&gt;=68 ~ 148 K）和出口压力（P-800 kPa）下的过冷沸腾临界热流密度<out>。本工作主要采用d=6 mm、L=60 mm（L/d=10）的铜镍合金（Cu-Ni 30%）管。内表面粗糙度（Ra）为0.15 μm。CHF，q_&lt;cr，sub&gt;，（35个点）与测量的出口和入口过冷度ΔT_&lt;sub，out&gt;和ΔT_&lt;sub，in&gt;的关系示出，流速作为参数。当ΔT &lt;sub，out&gt;和ΔT &lt;sub，in&gt;一定时，CHF随流速的增大而增大。这些说明了CHF随出口和入口过冷度增加而变化的趋势。当ΔT_&lt;sub，out&gt;和ΔT_&lt;sub，in&gt;分别大于30 K和40 K时，CHF分别为0. 001和0. 001，而当ΔT_&lt;sub，out&gt;和ΔT_&lt;sub，in&gt;分别大于0. 001和0. 001时，CHF分别为0. 001和0. 001。 关于我们 随着ΔT_&lt;sub，out&gt;和ΔT_&lt;sub，in&gt;的增大，温度升高，温度降低。随着ΔT_&lt;sub，out&gt;和ΔT_&lt;sub，in&gt;的增大，增加速率变小。由Eqs. (1)Bo=0.082{d/d &lt;σ/g（ρ_l-ρ_g）&gt;}^<-0.1>We^<-0.3>（L/d）^<-0.1>Sc^<0.7>（1），Bo=C_1{d/d &lt;σ/g（ρ_l-ρ_g）&gt;}^<-0.1>We-^<0.3>（L/d）^<-0.1>e^&lt;-（L/d）/C_2Re^<0.4>&gt; Sc^&lt;*C_3&gt;&gt;（2）其中，对于L/d [小于或等于]约40，C_1=0.082，C_2=0.53和C_3=0.7，对于L/d&gt;约40，C_1=0.092，C_2=0.85和C_3=0.9。ΔT_&lt;sub，out&gt;[大于或等于]30 K和ΔT_&lt;sub，in&gt;[大于或等于]40 K时的CHF数据与出口和入口过冷度的关联式（Eqs. (1)（2）.在低热流速度和高热流速度下，管材料对CHF的影响很小，尽管Cupro-Ni（Cu-Ni 30%）的热导率λ是SUS 304的2.1倍。从这一事实可以假设，与出口和入口过冷度的相关性（方程式）。(1)以及（2）不受管材料差异的影响。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