在能源工程中经常遇到各种瞬态非线性热传导问题，这类问题一般较为复杂，但若能将问题表示为一个变分原理，将便于采用各种简化方法进行求解，而在能源工程中遇到的瞬态热传导问题中，有许多是发生在温度单调变化的情形下，该文提出了这种情形下时间步上温度计算的变分原理并将其成功地应用于锅炉开停工过程中的锅筒壁温的仿真计算。图１表１参４ In energy engineering often encounter a variety of transient nonlinear heat conduction problems, such problems are generally more complicated, but if the problem can be expressed as a variational principle, will facilitate the use of simplified methods to solve, and in energy engineering Among the transient heat conduction problems encountered, many occur in the case of monotonous temperature changes. In this paper, the variational principle of temperature calculation in time step is proposed and successfully applied in the boiler open-shut down process Simulation of the wall temperature of the boiler. Figure 1 Table 1 reference 4