Engine coolant simulation rig

I'm trying to design a system to simulate the engine coolant temperature from engine start up to full load. In doing so, I have a hot coolant reservoir and a cold coolant reservoir, each with its own proportional valve provided with a single control which follows an input. The two fluids mix to give a resultant mixing temperature. The mixture ges into a storage manifold. From there on the mixture is pumped across one or three tanks (optional) while maintaining a constant differential pressure across the inlet and return. Thus the pump needs to be a variable frequency drive with a diff presure monitor, controlling the amount of flow depending on the load (one or two or three tanks). The return line empties into the initial hot and cold reservoirs. The flow required is a max of 15 GPM across each tank, thus the pump would be pumping 45 GPM max theoretically.

I have some specs of what I'm going to use. For the temperature control I have two proportional valves with an output control and a thermistor data logger which takes in multiple inputs and controls the temperature. However, if someone else has a better idea I'm more than open to it. For the pump, I presume I would need a smart pump or a VFD motor driven pump. Which is what I need advice on. The two tanks are open and at a height, thus the mixing tank is gravity fed.

I can also provide you with a bitmap of the control schematic and the overall scheme if you need.

My email is sushank. saha @ navistar. com