A novel positive displacement pump for spacecraft thermal control is being developed by AVS Added Value Solutions within the frame of ESA’s ARTES programme.
The most critical component of a Mechanically Pumped Loop (MPL) is the pump; a failure of the pump directly results in MPL system failure. Therefore, the reliability and lifetime requirements for the pump are extremely severe, resulting in a rather challenging pump design and development.
The PDPump is a diaphragm pump with passive reed valves. The pump has been sized in accordance with the current needs of thermal control systems for large telecom platforms.
The main requirements for the PDPump are:
- 15 years of continuous operation
- Working fluid: ammonia (also compatible with other fluids)
- Nominal volumetric flow rate: 100 [L / h]
- Nominal head: 1.5 [bar]
- Nominal inlet pressure: 50 [bar]
- Operational temperature range: -20 to +90 [°C]
- Tolerance to the presence of vapor at the pump’s inlet.
The novel design of the PDPump offers significant advantages from a tribology point of view in comparison with other known concepts (e.g. rotodynamic pumps, gear pumps, etc.). Rotodynamic pumps present additional drawbacks, including poor efficiency at low speeds, more difficult regulation and lack of self-priming capability. In contrast to rotodynamic pumps, positive displacement pumps offer several advantages, such as almost independent flow rate and pressure rise characteristics, self-priming capability, the capacity to handle large fractions of vapor, and reduced leakage problems (specially with diaphragm pumps).
The sizing of the PDPump has been carried out by means of a combination of analytical models for the critical elements, numerical models for the overall pump behavior and FEM analyses and CFD models for detailed design.
The critical elements of the pump have been verified at Breadboard level, including dedicated test rigs for the actuator, the pumping mechanism and the valves. The test data, in combination with the dynamic mathematical model of the pump and the FEM and CFD analyses, has been used as an input for the EM design. Performance tests at Breadboard level have already demonstrated a flow rate capacity of 100 [L / h].
In addition to the aforementioned tests, dedicated chemical compatibility tests and ultra-high cycle fatigue tests have been performed.