Mobile Air Conditioning (MAC) Working paper No. MACTP-1-3 (Geneva, 8 June 21) Test procedure development Progress update 8-6-21
Contents Project overview Progress made so far Identification of major influential parameters Definition of test plan Preliminary testing results 2
Project overview Goal: To develop test conditions and procedures for MAC Main evaluation parameter: impact on CO 2 / fuel consumption and other regulated emissions Procedure should be clearly discriminative of different systems Target accuracy and repeatability need to be clearly established 3
Project overview Definition of a test procedure(s) for MAC performance at type approval Focus on physical testing but with options to include virtual testing later. Procedure should provide the possibility (partial) substitution by virtual testing in the future Cost efficiency Realistic representation of MAC efficiency Use previous experience (ADAC 27, TNO 26) 4
MAC test conditions Which are the most important ambient conditions concerning the real operation of the MAC system? investigation of three typical climates hot: Athens medium: Frankfurt cold: Helsinki
% AC fuel consumption (of annual AC fuel consumption) 1 9 MAC test conditions - weather, e.g. Athens % AC fuel consumption of annual AC fuel consumption depending on ambient temperature 8 7 6 4 3 2 1 Athens 1 1 2 2 3 3 4 Temperature in C => proposal for test condition #1: 3 C/4%* *average relative humidity at 3 C 6 i.e. 7.% of the annual fuel consumption of the ac system is caused at ambient temperatures of 3 C (in Athens) 4 Athens % AC fuel consumption (of annual AC fuel consumption) 4 3 3 2 2 1 1 <1 1 14 1 19 2 24 2 3 >3 Temperature in C Solar radiation 7 W/m 2
MAC test conditions - overview 1 C/7% (3 W/m 2 ) 2 C/6% ( W/m 2 ) 3 C/4% (7 W/m 2 ) Based on assessment of annual weather data in Athens, Frankfurt, Helsinki. Remarks (results from simulation of refrigerant cycle): ±1 K at inlet temperature ( abient temperature) will result in a variation of ± % to 1% in cooling demand (greater impact at lower ambient temp.) ±3 % at inlet humidity will result in a variation of ± % in cooling capacity -> important for control of climatic chamber! 7
MAC test conditions - interior temperature Condensing the results for the three evaluated cities Findings: T cabin < T ambient From simulation work we suggest: 2 C and 4%? humidity in the test cell 21 C interior temperature Sensitivity tests: 3 C/4%, 23 C/% % AC fuel consumption (of annual AC fuel consumption) 4 4 3 3 2 2 1 1 Athens % AC fuel consumption (of annual AC fuel consumption) <1 1 14 1 19 2 24 2 3 >3 Temperature in C 4 4 3 3 2 2 1 1 Frankfurt4 % AC fuel consumption (of annual AC fuel consumption) <1 1 14 1 19 2 24 2 3 >3 Temperature in C 4 3 3 2 2 1 1 Helsinki <1 1 14 1 19 2 24 2 3 >3 Temperature in C 8
Factors to be considered in test procedure Option for test procedure: Test vehicle on the chassis dynamometer with and without MAC. Difference is the additional fuel consumption from the MAC system. Define following settings: 1. Test cycle ( easy to drive for repeatable results at small fuel consumption effects) 2. Ambient temperature and humidity 3. Interior temperature to be reached with MAC 4. Simulation of heat from sun radiation (with heater in vehicle or via 3.). Settings of the MAC system 6. Evaluation method for test results 9
Working hypothesis for test procedure Test programme on the chassis dynamometer for evaluation of: * different test cycles * different boundary conditions (T a, ϕ a, m a ), * settings of MAC (T i, mass flow m l, recirculating air by blower settings) * evaluation methods Tests at TUG, KTI and LAT for reproducibility and repeatability 3 mm T a, ϕ a 33 mm to roof blower m a m l T C3 To CVS, exhaust gas analyser g CO 2 /km Chassis dynamometer 1
Test cycles 7 6 Velocity Gear 4 km/h 4 3 Ti = const -> start test Bag 1 6 km/h ~ average speed of (NEDC+real world cycles) Bag 2 idling (long duration for repeatibility) 3 2 Gear MAC-2-Step cycle For for quick basic tests, preferred 2 1 1 1 1 2 2 Time [s] 14 12 BAG 1 (UDC) BAG 2 (EUDC) 1 velocity [km/h] 8 6 4 NEDC Option for not steady state test 2 2 4 6 8 1 12 Time [s] km/h 14 12 1 8 6 Preconditioning Urban CADC-Urban Part 1 Part 2 Part 3 Part 4 Part Preconditioning Road CADC-Road Part 1 Part 2 Part 3 Part 4 Par t Preconditioning Motorway CADC-Motorway Part 1 Part 2 Part 3 Part 4 CADC Measurement of additional fuel consumption from MAC in real world cycle (not planned for type approval) 4 2 1 1 2 2 3 Time [s] 11
Soaking / preconditioning Vehicle soaking: Vehicle soaked at 2 C for ~6 hours Similar to emission testing pre-test soaking Attainable at all type approval facilities Preconditioning phase: Start drive cycle @ 6 km/h Switch on MAC at desired setting* Start measurement once desired interior temperature is attained and stable *settings to attain desired interior temperature need to be determined (either by trial-and-error or by manufacturer specification) and validated before start of the official test. 12
Selection of the interior temperature (measurement point and settings) Different measurement points in the vehicle and different sensor options Position TC3 seems to be best option (representative for head/shoulder) 3 Temperatures measured at cabin rear middle 3 Temperatures measured at air vents outlet dashboard Temperature [ C] 2 2 1 1 Stratification of T in cabin Temperature [ C] 2 2 1 1 Chassis dyno, steady state at 6 km/h AC on, AUTO 19, C ventilator stage, heater on T at vents different PT1_1 PT1_2 PT1_3 PT1_4 Chassis dyno, steady state at 6 km/h AC on, AUTO 19, C ventilator stage, heater on TC1 TC2 TC3 TC4 2 4 6 8 1 12 14 16 18 Time [sec] 2 4 6 8 1 12 14 16 18 Time [sec] 3 2 Findings: *Radiation from vehicle interior makes preconditioning necessary (>6s) *T at vents outlet different and depending on MAC-comfort strategy of the model not recommended as reference *TC3 mid, not shielded best option? TC3 [ C] 2 1 1 preconditioning necessary TC3 (42) mid TC3 (4) mid TC3 (46) right TC3 (461) mid, shielded 2 4 6 8 1 12 14 16 18 Time [s] 13
Real world measurements in the project Main task: evaluation, if test procedure is representative? (due to very different climate conditions within Europe meeting exactly the average European MAC usage seems not to be the main goal. Covering the main influences for COP is more important) M-1.1) Parameterization and validation of the simulation of the sun radiation -> Park vehicles outside in sun (LAT, JRC) M-1.2) Influence of MAC in real world driving -> Measure real world cycles on the chassis dyno. Measure with PEMS after vehicles parked outside in sun (JRC, optional) chasing of 2 similar vehicles, one MAC off, the other MAC on. 14
Real world measurements in the project Ambient in-vehicle measurements (vehicle conditioned and then left parked under direct sunlight) Measured quantities: Solar power density [W/m 2 ] (top of the vehicle roof) Middle, front mirror [ºC] Head, driver [ºC] Head, front passenger [ºC] Floor, front passenger [ºC] Middle, by the gear lever [ºC] Head, middle back pass. [ºC] Trunk [ºC] 1
Solar Load options to include effect into test procedure Options (results from conference with Saint-Gobain Sekurit): 1) Calculate heat transmission by simplified approach: Measurement of direct solar transmittance (ISO 13837) of complete glazing, depending on average sun declination on each glass Calculating the total transmittance for complete glazing 2) Calculation of the thermal transfer: Calculating inner and outer surface temperatures for glazing & car body parts Calculating heat exchange by sun radiation, convection, conduction and emission 3) Detailed simulation with Open Source Tool (such as Energy+ for buildings) Option 1) may be the best approach for type approval. Option 2) and 3) may be considered if in future a shift towards virtual testing is desired. 16
Repeatability Influencing factors: 1. Variability in vehicle speed variability of engine power demand 2. Variability in temperatures and humidity during the tests influence on cooling demand and COP 1) Correct for variation of vehicle speed with measured braking forces of the rollers 2) Correct for variations of Ta, ϕa, TC3 with simulated cooling demand 3) Define a sufficient preconditioning phase (if too long, DPF regeneration may happen during test phase) Development of correction factors and procedures is in progress 17
Main open topics How can different settings of chassis dyno and of MAC be corrected. Can manufacturers make data for m air t 2,.. for different blower positions available for the actual study to test methods? discussion with ACEA (meeting in Graz on 3..21, collection of options ongoing) evaluation of different testing options to be finalized How can influence of sun radiation be depictured (in a simple way)? discussion of options with Saint-Gobain Sekurit ongoing Which vehicle velocities (or rpm for MAC) shall be used in the tests? 18
Thank you Thank you for your kind attention. 19