Procedure to assess the consumption and the thermal comfort of a passenger car MAC system

Transcription

1 Procedure to assess the consumption and the thermal comfort of a passenger car MAC system Carloandrea MALVICINO Centro Ricerche Fiat Strada Torino Orbassano Italy carloandrea.malvicino@crf.it Denis CLODIC Armines Centre for Energy and Processes

2 The procedure has been developed within the EU funded cluster Highly efficient air conditioning systems with near zero green house gas emissions and elimination of hydrofluorocarbon (HFC) Two projects form the cluster: : Low Cost and High Efficiency CO2 Mobile Air Conditioning System for Lower Segment Cars TopMacs: Thermally OPerated Mobile Air Conditioning Systems The procedure is conceived as a proposal for a common method to qualify the Mobile Air Conditioning System so to compare systems based on different approaches or technologies.

3 Consortium - Low Cost and High Efficiency CO2 Mobile Air Conditioning System for Lower Segment Cars - is a project funded by the EU in the 6th framework Consortium Main Objectives Development of a low cost and high efficiency air-conditioning system based on CO 2 (R744) for A, B and similar vehicles (low C class or LCV) CENTRO Definition of agreed methods to assess: performance fuel annual consumption environmental impact

4 Objectives Assessment of the MAC system fuel overconsumption during a realistic cycle and under representative climate conditions The procedure should be suitable to the major part of available testing facilities The comfort level as well the performance severe conditions have to be considered The data should be useful to estimate the LCCP

5 Thermal Condition Definition The MeteoNorm Data Base has been used The average conditions have been calculated for each country excluding the nigh time (from 8 p.m to 8 a.m.) and all the hours where the air temperature was lower than T ref. (23 - AC switch ON threshold) The European Average Summer Conditions have been calculated weighing the values of each country with the number of car sold Temperature ( C) R.H. (%) Irradiation (W/sqm) Occurence Frequency Millions of sold cars/year Low Countries % 1.0 Greece % 0.3 Germany % 3.8 Portugal % 0.2 United Kingdom % 2.6 Spain % 1.3 France % 2.1 Italy % 2.4 Northern Countries % 0.6

6 Thermal Condition Definition Most of the climatic chambers equipped with rolling bench haven t any lamp or use lamp with a non-appropriate spectrum This could represent a problem for the procedure application So, by means of a simple cabin thermal model (one-node, steadystate), equivalent conditions have been identified without solar irradiation Temperature ( C) Ambient Conditions Irradiation (W/sqm) R.H. (%) Cabin Conditions Cabin Temperature ( C) Air water content (g h2o /kg air ) Thermal Load (Watt) Sensible Latent Total Average European Summer conditions Test 1 - Equivalent European Summer conditions Test 2 - Severe Summer conditions Test 3 - Dehumidification

7 Proposed Tests Mean European Summer Climate Conditions 28 C 50% R.H Test => Cabin Temperature Set Point: 20 C Severe Summer Conditions 35 C 60% R.H Test => Cabin Temperature Set Point: 23 C Mid Season Conditions 15 C 70% R.H Test => Cabin Temperature Set Point: 20 C

8 Cabin Set Point Two cabin temperature set points have been identified: T cab_1 = 20 C mild external and dehumidification conditions T cab_2 = 23 C severe summer conditions The choice to define two different cabin set points is in agreement with the adaptive comfort theory The car manufacturer has to indicate the correct A/C setting corresponding to the recommended cabin temperature. A specific procedure has been defined for the manual systems

9 Driving Cycle The European average travelled distance ranges from 10 to 20 km and the average speed is varying form 25 to 40 km/h - source INRETS - A modified NEDC cycle has been proposed Temperature ( C) Cool Down High Speed Cabin Temperature Outlet Temperature Speed Stabilisation Speed (km/h) Time (min) The additional four elementary urban cycles (ECE) have been included consider the effect of the cool-down transient and the behaviour of the MAC system in steady state condition during the urban cycle. The fuel consumption measured will be calculated as follows: 1 st ECE consumption/2 + EUDC consumption + 2 nd ECE consumption/2

10 Testing Facility Thermal regulation of the climatic chamber Thermal Manikins to assess comfort Driver Fan Rolling bench Emissions and Consumption measurement system

11 Thermal Comfort Assessment The Thermal Comfort can be measured with Manikins able to measure the Operative Temperature and local air speed Conventional instruments, previously calibrated with the thermal manikins Anemometer Heated Sensors Skin Elements Relative Humidity and Air Temperature sensors The CRF mainkin is based on the skin elements concept. Each sensor measures the: Equivalent Temperature Mean Radiant Temperature Air temperature, humidity and local speed The manikin is light ( less than 20 kg) The acquisition system can to interface up to 4 manikins wireless The Software allows the estimation, in real time, of the perceived thermal comfort A specific model of the human thermoregulatory system allows the evaluation of different clothing and metabolism

12 Thermal Comfor Assessment The Thermal Comfort level is measured in 4 points TC 1 = > 300 seconds (cool down) average on 30 seconds. TC 2 = > seconds average value TC 3 => seconds average value TC 4 = > seconds average value Minimum threshold level can be identified for each point A synthetic value (TC) is then calculated using the following expression: TC = 0.2 TC 1 + TC2 + TC TC 4

13 How Themal Comfort Value is used The Thermal Comfort value is used to exclude the systems that generates a Thermal Comfort below the identified thresholds

14 An application example 9 8 Segment A Gasoline Segment B Diesel Segment B Diesel Segment B Diesel Segment C Gasoline Segment C -4-Hybrid Segment D Diesel Segment D Gasoline Segment A Gasoline Segment B Gasoline Segment B Diesel Segment C Diesel Segment C Diesel Segment C -5-Hybrid Segment D Gasoline Better Comfort Comfort Index (A.U.) Lower Consumption Fuel overconsumption (l/100 km)