Accumulators are handled as follows:
If the flow is positive in the node with the accumulator (power is stored in the accumulator), the temperature in the return part of the network, Tr, will be the same as the minimum temperature for the accumulator, Tmin.
If the flow is negative in the node with the accumulator (power is recovered from the accumulator), the temperature in the supply pipe part of the network, Tf, will be equal to the max. temperature for the accumulator, Tmax.
If the accumulator power is known and the accumulator's average temperature falls below Tmin, it will not be possible to recover energy from the accumulator in the next time step. Similarly, if the temperature is above Tmax, it will not be possible to store any energy in the accumulator in the following time step.