Under thermodynamic parameters dependency type the values i input temperature as function of time.

In addition, the pressure was left constant under thermodynamic parameters. The system I'm running is a cylinder (solar cooker with heat pipes inside) with a user defined paraffin inside the enclosed fluid subdomain. The problem I'm having when running this transient analysis is the temperature of a point goal goes from a starting ambient temperature at 27 C and goes down when I'm heating the sytem up. Also, it doesn't make sense at a constant value it stays at 25 C, which is not correct either. I'm attemping to simulate the temperature of the paraffin, so i can find out what the temperature of the fluid is because i have four heat sources at the bottom simulating heat pipes. The liquid paraffin is located in the light blue in the Figure below. If the cooking surface is the dark blue section in the Figure below, which i want to know the temperature for. Also, i was thinking of using an equation, i have seen the nusselt number and reynolds number being used, but got bad results from that approach as well. How can i fix the temperature dependency to do this?