HVAC
SYSTEM
DIGITAL TWIN
Modelling every part of a complex machine —
the example is a data centre cooling circuit
WHAT IT IS
A machine modelled component by component, from data sheets and physics, validated on the bench
CHALLENGE
A system-level model tells you the machine works; it cannot tell you what any one component inside it is doing
RESULT
A digital twin in which every state of every component can be simulated and tracked
01
CHALLENGE
A complex machine is not one thing behaving in one way. An HVAC unit cooling a data centre is pumps, valves, heat exchangers, bends, strainers and flow meters, and its behaviour is what all of them do to each other under a given load.
Model it at system level and you get a machine that works on paper. What you do not get is what any single component inside it is doing — which valve is throttling, how much head the pump is actually producing, where the pressure is being lost and why the second circuit is starved. Those are the questions that come up when something goes wrong, or when someone asks whether a different configuration would be better.
Measuring all of it on the real machine is not an option either. There are not sensors on every branch, and there never will be.
02
SOLUTION
So we model every single component, one at a time, and keep it. Over the years that has become a library of validated components — pumps, valves, exchangers, bends, strainers, flow meters — which is what makes the next machine a matter of assembling parts that are already trusted rather than starting again.
Each one starts from its technical data sheet — the manufacturer’s geometry, coefficients and curves — and then the physics that governs its behaviour is implemented: the equations for the pressure drop across a bend, the characteristic of a pump, the transfer in an exchanger, the loss coefficient of a valve as a function of its opening.
Every component is then validated against experimental data and laboratory testing, because a data sheet describes the part the manufacturer sold, not the part in this circuit at this duty point. That step is what separates a model from a diagram.
Assembled, the components become a circuit: the user picks them, connects them, sets the operating conditions and runs the simulation. In the demonstrator, a hot circuit and a cold circuit share a heat exchanger, with a bypass valve, a modulation valve, a butterfly valve, a check valve, a strainer and a flow meter between them, and the controllable elements can be switched and set case by case.
03
RESULTS
What comes out is the digital twin of a physical device: a model in which every state of every component can be simulated and tracked, not only the inlet and outlet of the machine as a whole.
That makes questions answerable that were previously arguments. Run one pump with part of the circuit bypassed, and read the speed, power and head it settles at. Close the bypass and see the pressure drop rise and the pump work harder. Run two pumps at reduced speed for the same head, and compare the power. Replace a butterfly valve with a strainer and watch the head demand move again.
Each of those is a case run in seconds against a model whose components have been checked against the bench, rather than a change made on the real machine to find out.
It is also the foundation the next thing needs: a twin that tracks every internal state is what you compare live sensor readings against, and the divergence between the two is an early warning.
