A test bench for heat pumps measures a performance map. The map shows the heating capacity and the coefficient of performance as a function of the source and sink temperature. The test bench also does defrost cycles, part-load tests and endurance tests. Profectronics builds the system that conditions the source and the sink, operates the test specimen and records the result with traceability.
The test point A2/W35 to EN 14511 does not show the behaviour at a source temperature of −7 °C and a flow temperature of 55 °C. It also does not show the effect of a defrost cycle every 12 min on the operation. For this reason, the test bench covers the full operating range of the unit.
The test bench replaces the environment of the unit. It keeps the source at the specified temperature. It removes the heat from the sink with a control loop.
| Circuit | Medium | Range (design) |
|---|---|---|
| Source brine/water | Water-glycol, water | −15 to +40 °C |
| Source air | Climatic chamber, temperature and humidity controlled | −25 to +55 °C |
| Sink heating | Heating water | up to 80 °C |
| Flow rate per circuit | controlled | 0 to 30 L/min |
| Control deviation | steady state | ± 0.2 K |
In air operation, the approach flow sets the quality of the performance map. The conditioned air moves in a closed circuit through distributor plates and then in laminar flow through the chamber. As a result, the temperature and the humidity are the same across the full inlet area. An imbalance of 2 K across the inlet area makes the performance map incorrect.
For heat exchangers, Profectronics builds calorimeters: for condensers, gas coolers, coolers, charge air coolers and oil coolers. The values that follow apply to the calorimeter and not to the conditioning of the heat pump.
Profectronics designs the test benches for the standards that follow. The functional specification defines the test points from the standards.
The proof includes the measuring chain behind the reference to the standard:
Test specimens also operate with propane (R290, safety group A3) or with CO₂ (R744). R290 is flammable. R744 operates in the supercritical range. Profectronics also designs the test benches for refrigerants of the safety groups A1, A2 and A2L.
The warning logic and the fault logic are part of the system. The risk assessment for each refrigerant and installation site sets the necessary safety level (performance level, zones, extraction capacity).
The table gives the limits of the modular system.
| Feature | Value (design) |
|---|---|
| Test specimens | Brine/water, water/water and air/water heat pumps, chillers, domestic hot water heat pumps |
| Sink | up to 80 °C |
| Source | Brine −15 to +40 °C, air −25 to +55 °C |
| Circuits | Source and sink with separate control (brine and water) |
| Refrigerants | Safety groups A1, A2, A2L and A3, with R290 and R744 (CO₂) |
| Standards | EN 14511, EN 14825, EN 16147 |
| Unattended operation | up to 72 h |
| Construction | Frame, control cabinet, as an option container or climatic chamber |
The values are design limits and not a commitment for a specific project. The functional specification defines the values for your system before Profectronics orders the hardware.
For the design, 5 items of data are sufficient: test specimen, medium, ranges for pressure, flow rate and temperature, installation site and date. A customer specification helps, but it is not a condition.
