E-Mobilität: Pressure Testing
Thermal Management & Cooling Circuit
Quality Control
Pressure Cycle Testing
In a vehicle, media-carrying components must withstand extreme strains at temperatures ranging from -40° C to +140° C. Poppe + Potthoff Maschinenbau develops testing systems to check and optimize them efficiently.
Putting Components
To the (pressure-) TEST
Cooling and heating systems are essential for electronic vehicles: they protect against overheating of essential components for the operability of the vehicle and ensure comfort. In order to validate them for use, components are put to the test under changing pressure and temperature conditions. The performance and power consumption of the systems must also be checked in realistic service life tests so that the air conditioning unit and other electronic components do not limit the range of the vehicle. The BMW M-07 is an example of a test standard for a pressure cycle test under changing temperature conditions, as well as an overpressure and underpressure test.
Climate control systems must be able to withstand extreme load changes. Instead of testing the load-bearing capacity in proprietary test setups or in real operation, manufacturers can now analyse their products in pressure cycling and function test benches from Poppe + Potthoff Maschinenbau.
Pressure Load Changes
at -40 to +140 Grad Celsius
In a typical test, the component is inserted into the test chamber of the pressure cycling test bench. This can be an auxiliary heater for an electric car or valves, hoses and other hollow bodies that need to withstand more than 100,000 load changes over the lifetime of the vehicle (up to 15 years). The test medium is a water-glycol mixture or pure glycol (for example Glysantin G40, G44, G48). The cooling circuit is tested at -40°C to +20°C (-40°F to +68°F) while a heating circuit is tested in temperatures from +20°C to +140°C (68°F to 284°F). A specially developed closed test media circuit uses pressure to prevent the formation of alcoholic vapours (which create a risk of explosion). A system can also be analysed in a climate chamber.
The compact pressure cycling test bench from Poppe + Potthoff Maschinenbau tests climate components at -40 to +140 degrees Celsius. Temperature, volume flow and pressure changes can be freely programmed in sinusoidal and trapezoidal form and enable fast and economical testing.
The flow rate of the test medium can vary from 1-50 l/min at a pressure of 0.2-12 bar or higher. The load changes are freely programmable with a sinusoidal or trapezoidal rise at a test frequency of 0.2-2 Hz or faster. The test stand can be used for complete systems, assemblies and components made of various plastics, metals and sealants. Weak points in the material combination – for example around a weld seam – can be sounded out and optimized early in the development process as well as during production.
Time-lapse for long-term tests
A long-term test usually takes 20-30 days, depending on the frequency of the load changes. The temperature and volume flow of the test medium as well as the ambient temperature (if the test takes place in the climatic chamber) vary according to the test specification. The temperature at the inlet and outlet of the test object is measured continuously, as well as the flow rate, pressure and pressure drop, and current and voltage (both in the high and low range). The focus is on the thermal and electrical performance of the heating and cooling unit under varying environmental conditions. Thermal sensors can be mounted on the product to indicate during the test when energy is lost (thermal bridges) or when the component becomes very hot (and thus presents a fire hazard).
Safe and easy to use
Poppe + Potthoff Maschinenbau test systems are easy to operate and extremely safe. The test chamber consists of welded stainless steel and a high-strength polycarbonate safety window. Any test sequences created on the PC can simply be called up manually via coded recipe management or by a handheld scanner. The integrated LabView software from National Instruments enables efficient data acquisition and visualization. Test procedures and data are automatically stored on the system and can be exported to the network for evaluation. The open software structure makes it possible to integrate additional sensors and data during testing. Poppe + Potthoff Group can provide numerous testing services, remote maintenance and on-site technicians, if necessary.
Temperature ambient: -40°C to +160°C with rate of change 1,5 K/min
Temperature fluid: -40°C to +135°C
Test chamber: with Ex protection for pressure test with coolant (ATEX)
Size of test chamber: 1,500 x 900 x 900 mm (W x H x D)
Flow rate coolant: 0,5 l/min up to 30 l/min adjustable
Test pressure: dynamic 0,2 to 6 bar with sinus- and trapezoidal curve
Frequency: up to 2 Hz (further frequencies upon request)
Pressure drop test: up to 1,000 mbar
Static pressure test: up to 20 bar with compressed air and adjustable pressure increase
Leak rate test: 0,5 cm3/min
Vacuum testing: Pressure variation between atmosphere and 18 mbar abs.
Energy efficiency in battery operation
In addition, Poppe + Potthoff Maschinenbau offers a function test bench for electrical appliances such as cooling and heating units, control valves and pumps. Power consumption and performance are typically tested at alternating temperatures – optionally with a low- or high-voltage power supply to simulate operation via onboard battery and generator or the traction accumulator. In many EVs, the heating and cooling systems drain the battery and negatively affect the vehicle’s range. A comparison of test results before and after a load
test on the pressure cycling test bench can show how power consumption and performance change over the vehicle’s service life. The test object is connected to the power supply (low voltage 0-20VDC/5A) or high voltage (0-600VDC/150A) and the test media circuit. The test medium is circulated at a temperature of between -35°C to +100°C (-31°F to +212°F) and a flow rate of 1-50 l/min. The test can also be carried out in a climatic chamber at -40°C to +140°C (-40°F to +284°F) simulating changing ambient temperatures.