七节点模型（Seven-node Model）

$$C_i \frac{dT_i}{dt} = \sum_{j=1}^{7} Q_{i,j}^{cond} + Q_i^{ext} + Q_i^{int}$$

$$Q_{i,j}^{cond} = \frac{k_{ij}A_{ij}}{d_{ij}}(T_j - T_i)$$

$$Q_{i,He}^{conv} = h_i A_i (T_{He} - T_i)$$

$$Q_1^{ext} = \alpha I_{sun}\cos\theta \cdot A_{proj} + Q_{albedo} + Q_{IR,earth} - \varepsilon\sigma T_1^4 A_{skin} - h_{ext}(T_1 - T_{air})$$

$$Q_2^{ext} = \varepsilon\sigma T_{earth}^4 A_{proj} - \varepsilon\sigma T_2^4 A_{skin} - h_{ext}(T_2 - T_{air})$$