DV+IR, which is below the defined maximum and thermally rated as being comfortable [3]. ... Notable differences were observed between the temperature .... time, participants were entertained with either crossword puzzles and Sudoku grids.
Civil-Comp Press, 2016 Proceedings of the Third International Conference on Railway Technology: Research, Development and Maintenance, J. Pombo, (Editor), Civil-Comp Press, Stirlingshire, Scotland.
Paper 0123456789
Passenger Comfort for the Next Generation Train: Subject Trials for Ventilation and Lighting J. Winter1, I. Windemut1, N. Kevlishvili1, D. Schmeling2 and J. Maier3,4 1
Institute of Vehicle Concepts, German Aerospace Center, Stuttgart, Germany Institute of Aerodynamics and Flow Technology German Aerospace Center, Goettingen, Germany 3 Institute of Aerospace Medicine German Aerospace Center, Hamburg, Germany 2
Abstract Excellent passenger comfort should become a competitive advantage for railways again. For a long time railways have lost the alignment to other modes of transport as for example automobiles. In the frame of the Next Generation Train project plenty of passenger comfort aspects, including ride smoothness, vibration, acoustic noise, pressure fluctuation, lighting, and air-conditioning in high-speed trains are addressed. The current paper is the third one in a series [1, 2] giving a comprehensive overview on the passenger comfort activities at the German Aerospace Center since 2007. In this concluding paper the results of laboratory trials on ventilation and lighting with human subjects are presented. In particular, we describe two studies performed for analysing the thermal comfort of displacement ventilation with air outlets installed under the passenger seats and the pilot study of infrared heating via a panel installed in front of the first row. Further, in two tests, the comfort perception of passengers subjected to a new lighting concept with OLEDs was assessed. Due to the OLEDs’ properties, such as diffuse light with no glare and a warm colour appearance of the light source, subjective comfort is achieved even with the lower average illuminance than defined by EN 13272:2012. Finally, an outlook is given. Keywords: passenger, comfort, air-conditioning, lighting, noise, pressure, vibration, ride-comfort, ventilation, heating, HVAC.
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Introduction
Research on passenger comfort within the Next Generation Train (NGT) project is among others aiming to introduce a designing procedure for railway car interiors. To give advices for a straight forward development of railway car interiors providing excellent individual passenger comfort, functional requirements and their cross-
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correlations are needed. Based on the analysis of single comfort factors in a railway car cabin, a matrix of interdependencies will be built-up step by step. After a general overview on the work done so far [1], the set-up of the new generic laboratory for “standard” double-decker railway cars [2] is given. By means of the generic laboratory the research on comfort factors missing yet will be driven ahead. This paper presents first results of subject trials determining comfort factors of displacement ventilation, infrared heating and lighting as done within the last two years.
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Ventilation
Pilot studies in the generic laboratory aimed at analysing the thermal comfort of displacement ventilation and an infrared heating panel. Newly developed air outlets were designed and installed under the passenger seats. Outlets were fixed under the passenger seats and were suitable to supply a sufficient amount of fresh cool air with low speed to the cabin (see section 3.1 in [2]). The exhausted air left the cabin via slots at the left and right upper part of the laboratory. Additionally, an infrared (IR) heating panel was developed [7]. For these pilot studies it was installed in front of the first passenger row (green rectangle in Figure 1). It had 1000 watts and was used with 50 % nominal capacity, resulting in a surface temperature of 50 to 65 °C.
2.1 Study design and instruments Two studies were performed, with a cabin interior comprising 20 seats in 5 rows. In both studies, the newly developed climate components were used as independent variables: displacement ventilation (DV) was compared with displacement ventilation plus IR-heating (DV+IR). The average target temperature was 24 °C, relative humidity was intended to be a maximum of 60 % and air velocities should be less than 0.36 m/s. In both studies, half of the subjects were female (n = 10), half male (n = 10). Mean age was 32 years (standard deviation [SD] = 7.5). All participants wore standardised clothing (= 1 clo) with long sleeves and trousers, and no boots or scarfs were allowed. To measure the climate situation in the cabin, the laboratory was equipped with several sensors according to EN 13129 (see section 3.2 in [2]). Data loggers were attached to every single seat to measure temperature and humidity. A hot-wire anemometer was used to determine air velocity before the experiments started. Air velocity was measured in DV only. Subjective data were assessed using established psychological questionnaires which were administered on PDAs (HP iPAQ214). Participants rated the perceived intensity of climate parameters (temperature: 1 = very cold to 7 = hot; air draught: 1 = not at all to 7 = strong; humidity: 1 = very dry to 7 = very humid; air quality: 1 = very sticky to 7 = very fresh) and the corresponding comfort level (five-point rating scale, ranging from 1 = very uncomfortable to 5 = very comfortable). Finally, a general satisfaction judgement was given. Additionally, subjects answered scales concerning well-being, personality, odour and demographic data.
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The procedure was standardised in each study: While the target climate was adjusted, participants acclimatized to the climate situation. Each scenario was then presented for 15 minutes (in both studies a different order was used: DV – DV+IR vs. DV+IR - DV). For their entertainment, subjects read a railway magazine (DBmobil) during this time. After the set exposure time, subjects had about 15 minutes to fill in the questionnaire. The next climate scenario was then implemented. The whole procedure lasted 1.5 hours.
Figure 1: Experimental situation in the generic laboratory
2.2 Results The average temperature in the laboratory was 23.5 °C in DV and 23.52 °C in the DV+IR-scenario. Average relative humidity was 39.7 % in DV and 39.8 % in DV+IR, which is below the defined maximum and thermally rated as being comfortable [3]. Because of the use of air distribution bags [2], average air velocity at the passenger seats was very low (< 0.02 m/s). In both test conditions a similar average climate situation was successfully realized. To analyse the questionnaire data, multivariate analyses of variance (MANOVA) with repeated measures and t-tests for paired samples were calculated. MANOVAs were used for the comparison of mean differences as multiple dependent variables had been tested repeatedly. The associated F-statistic indicates the results’ significance depending on the degrees of freedom (df). The effect size is expressed as ηp² which represents the proportion of variance explained. T-tests for paired samples were used to make single comparisons of two dependent means (test statistic “t”). The subjects’ results show that in sum, the integration of both climate components in the generic laboratory was successful. On average, both components were rated as being more or less comfortable – although air quality was slightly lower and less comfortable when the infrared heating panel was operating (Table 1). 3
Temperature Air draught Humidity Air quality
M SD M SD M SD M SD
DV 3.51 1.12 2.97 1.56 3.44 .94 4.10 1.25
Perception DV+IR 3.69 1.24 2.97 1.66 3.38 1.09 3.85 1.23
ηp² .02 .00 .00 .07+
DV 2.85 1.11 2.95 1.00 2.97 .87 3.23 .90
Evaluation DV+IR 2.85 1.01 2.90 1.14 2.92 .90 2.97 .87
ηp² .00 .00 .00 .08+
Note. Rating scales perception: Temperature: 1 = very cold to 7 = hot; air draught: 1 = not at all to 7 = strong; humidity: 1 = very dry to 7 = very humid; air quality: 1 = very sticky to 7 = very fresh; rating scale evaluation: 1 = very uncomfortable to 5 = very comfortable; ηp² = effect size; +p < .10
Table 1: Descriptive statistics of climate parameter perceptions and evaluations In addition to analysing the global thermal situation in the generic laboratory, the mock-up was analysed row-wise. It was found that air velocity was very low in all rows (max. 0.018 m/s). Especially in the middle row, constant and low values were measured (Figure 2). Notable differences were observed between the temperature conditions in the five seating rows: for both climate scenarios the highest temperatures were measured in the front rows (Figure 3). In both scenarios – independently from using the IR-heating panel – temperature decreased by 1.5 °C from row two to five. This effect can be explained by the interior of the generic laboratory: in front of the first row there was an open space. Cool fresh air from beneath the front seats gathered there thus implicating less cool air at the passengers’ seats in the first rows. 0.05
0.04
0.03 Air draught measurement DV
0.02
0.01
0 Row 1
Row 3
Row 5
Figure 2: Air velocity in m/s per row
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25.0
Temperature °C
24.5 24.0 Temperature measurement DV
23.5 23.0
Temperature measurement DV+IR
22.5 22.0 21.5 Row 1
Row 2
Row 3
Row 4
Row 5
Figure 3: Temperature in °C per row Taking into account subjective perceptions of the surrounding temperature and air flow, a somewhat different picture arose for the seating rows: in the first row, temperature was perceived as being higher in the DV+IR-condition than in the DVcondition (T(7) = -2.55, p < .05, Figure 4).
Air draught: 1 = not at all to 7 = very strong; Temperature: 1 = very cold to 7 = hot
5.00 4.50 Air draught perception DV Air draught perception DV+IR Temperature perception DV Temperature perception DV+IR
4.00 3.50 3.00 2.50 2.00 1.50 1.00 Row 1
Row 2
Row 3
Row 4
Row 5
Figure 4: Subjective temperature perception per row
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Accordingly, the air draught perception in the first row was a little lower in this condition (n. s.). Corresponding to the measurement values, air draught perception had a u-shaped course throughout the laboratory in DV and DV+IR: In the middle row, air draught was perceived as being very low, especially in the DV-condition. Comfort evaluations for both climate parameters increased from row one to four and decreased again in row five. Further differences were identified for the subjects’ body parts. In both climate scenarios, temperature stratification was found between head and feet (F(3,4; 128,9) = 30,62, p < .01, ηp² = .45): at the head, temperature was higher than the average; at the feet it was lower. The opposite effect was found for air velocity (F(2,8; 106,2) = 19,36, p < .01, ηp² = .34): at the head, lower air draught was felt while at the feet, the perceived air draught was higher than the average. Generally, higher temperature ratings and lower air draught ratings went along with higher comfort judgements.
100% 90% 80% 70% 60%
satisfied
50% neutral
40% 30%
dissatisfied
20% 10% 0% DV
DV+IR mixed ventilation (aircraft cabin)
Figure 5: Satisfaction ratings for different climate conditions.
The satisfaction ratings are summed up for the different climate scenarios (Figure 5). Results are compared with findings from thermal comfort experiments with a comparable group of subjects in an aircraft cabin which had the same temperature level and the same volume flow ratio per passenger: The biggest proportion of satisfied and the smallest amount of dissatisfied subjects was found for displacement ventilation. Mixed ventilation provided dissatisfying climate conditions for about one third of the participants. All in all, only a small proportion of the subjects was dissatisfied with displacement ventilation – with or without infrared heating panel.
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2.3 Conclusion Concluding from these pilot studies, displacement ventilation is a very promising ventilation principle. The integration of further climate components like an IRheating panel needs special attention and has to be analysed further. Expanded studies including e.g. better isolation of the laboratory, broader measurement equipment and a fully operable air conditioning system will produce insightful results regarding the thermal comfort for railway passengers. Altogether, these pilot studies prove that the generic laboratory provides a solid testing environment for the analysis of subjects’ thermal comfort.
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Lighting
The generic laboratory was further used for the analysis of a new OLED (organic light emitting diodes) luminaire. OLEDs are homogeneous area light sources that produce diffuse light with no glare and excellent colour rendering (CRI > 90) [2]. It is assumed that with OLED lighting, a highly effective lighting solution for the NGT is realized because of its low maintenance and small installation space demands and its low power consumption. Additionally, OLEDs should establish a very comfortable lighting situation for the passengers.
3.1 Study design and instruments In a first step, the mock-up was equipped with a lighting system according to the NGT lighting concept (see also sections 2 and 3.3 in [2]). Square OLED modules with dimensions of 99 mm x 99 mm and a colour temperature of 4,000 K (neutral white) were used (Figure 6). The OLED panels were dimmable between 0 % and 100 % continuously. The whole luminaire consisted of 152 OLED modules, installed in two rows symmetrically to the mock-up midline. The modules were closely attached to each other, visually resembling two continuous luminous lines (Figure 6).
Figure 6: Luminaire layout in the generic laboratory
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In a second step, a subject test was performed, to analyse the lighting comfort of the OLED luminaire in the generic laboratory (Figure 7). Forty subjects took part in two experiments. Two lighting scenarios (100 lx and 150 lx) and two kinds of activities (puzzles and PDA game) were used as levels of the independent variables in a two-factor-within-subjects design with repeated measures.
Figure 7: Experimental situation in the generic laboratory Illuminance was measured using a Luxmeter Voltcraft LX-1108. The measuring points were located in seating areas according to the standard EN 13272:2012 at every seat on a horizontal level, at a height of 0.8 m above floor level and 0.6 m in front of the back rest, at the centre line between the lateral margins of the seat. Subjective data on lighting comfort were gathered using different questionnaires: Participants rated their perception of four lighting parameters, namely (a) brightness, (b) CCT (correlated colour temperature), (c) glare and (d) visual performance. In a second step, the corresponding comfort level was evaluated. Further questions covered states of mood, sleepiness, well-being, personality, lighting preferences and expectations as well as demographic data. All items were administered on PDAs. The procedure was as follows: after an adaptation phase, each lighting scenario was presented twice and in a reversed order for 10 minutes. During the exposure time, participants were entertained with either crossword puzzles and Sudoku grids or a simple game on the PDA. Subsequent to the exposure time, subjects had ten minutes to fill in the questionnaire while the lighting situation remained unchanged. In between two lighting scenarios, neutral light (10 lx) was turned on for 1 minute.
3.2 Results Results of the illuminance measurement are as follows: The minimal illuminance value of each lighting scenario (150 lx, 100 lx) was achieved at every seat. As a consequence, average illuminances were higher than planned: 201 lx in the 150 lx
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scenario and 133 lx in the 100 lx scenario. Across the seating rows, illuminance was higher at the aisle seats compared to window seats: the mean difference was 32 lx in the 100 lx condition and 48 lx in the 150 lx condition. The assessment of subjective data showed that subjects felt neutral to rather comfortable in both lighting conditions. Although an average illuminance of 100 lx is darker than the minimum illuminance as defined by EN 13272:2012, no comfort restrictions were observed for this condition. On the contrary, subjects felt less blinded in the 100 lx condition and consequently evaluated it as being more comfortable regarding this lighting parameter. Personal characteristics (individual lighting preferences and expectations) influenced the perception and evaluation of different lighting parameters [4]. Interestingly, no differences in subjective perceptions were found between seat rows; evidently, objective differences in illuminance levels were too small to influence subjective comfort evaluations. Compared to high power LEDs, which had been analysed in a similar experimental setting in a previous project (Project LiKab, supported by the Federal Ministry of Education and Research, grant number 03CL08, [5]) that was conducted in an aircraft cabin, OLEDs were rated as providing more lighting comfort: While both types of luminaires were perceived as being comparably bright by the subjects, light emitted by OLEDs was observed as being less glaring and having a warmer appearance (Figure 8). In sum, subjects were more satisfied with the newly developed OLEDs and evaluated all three lighting parameters as being more comfortable (Figure 9).
Figure 8: Comparison of the perception of lighting parameters for OLEDs and LEDs
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Figure 9: Comparison of the evaluation of lighting parameters for OLEDs and LEDs
3.3
Conclusion
Results from two subject tests in the generic laboratory show, that lighting comfort is given when the NGT lighting concept is implemented. Moreover, this lighting installation using OLEDs has some advantages regarding subjective comfort parameters compared to a LED-lighting system – even though the average illuminance was darker than the minimum illuminance as defined by EN 13272:2012. Psychological research questions like the influence of personal preferences and expectations on lighting comfort sensations are of special interest. Their analysis based on data assessed here provides further insight in the processes that underlie lighting comfort sensations [4].
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Outlook
The intention of the series of three papers ([1], [2] and current one) was to provide a comprehensive overview on all aspects of passenger comfort under investigation at DLR. In general there are two different areas to consider: • The way of a passenger to get to his seat in a railway car • The ride on the train itself The first issue can be solved mainly by construction, services, and communication 4.0 to make the logistic task “move from A to B” much more seamless – normally it is intermodal. Thus, a special focus will be on providing an easy change of train, easy access, and a stress-free change of transport mode in a 10
Next Generation Station (NGS) [6] (Figure 10). As the trains are stretched up to 400 m, the NGS would work with mainly vertical passenger paths by means of escalators and lifts. Such a tower station of a mega-city needs a significantly smaller parcel of land than an agglomerate of long distance, regional, and urban traffic stations along with associated parking areas. A future vision is that local emission-free, hydrogen or hybrid private cars, taxis and busses can drive directly into the lower level of the NGS to optimise connections. The NGS is planned to be constructed fully covered with partial or full air-conditioning.
Figure 10: Next Generation Station (NGS) as an intermodal node
Figure 11: Arrival of the Talent2 control car at DLR
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The second issue is addressed by creating an innovative process allowing for a straight-forward development of a railway car interior. The basic definition of comfort factors describing the passengers’ well-being in a temporary “living room” is on its way. Different laboratories are in place already and first investigations with manikins and test subjects have been done. The results are described here. In the next step data for further comfort factors will be collected. A big step forward will then be to investigate the dependencies of all identified comfort factors. With the help of this dependency matrix the specification of a passenger friendly interior of a railway car can be achieved. For the verification of laboratory results, DLR is opting for a research train. In the meantime an original control car of Talent2 train (Figure 11) was bought and is ready to be moved into a new laboratory building under construction. The control car meanwhile is mounted on its original bogies again. Once in place, it is planned to investigate the thermal transfer path as well as noise paths through the car-body walls by means of this laboratory set-up.
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J. Winter, I. Windemut, N. Kevlishvili, D. Schmeling and J. Maier, Passenger Comfort for the Next Generation Train: Laboratory for Comfort Factor Trials, in J. Pombo, (Editor), Proceedings of the 3rd International Conference on Railway Technology: Research, Development and Maintenance, Civil-Comp Press, Stirlingshire, UK, 2016. J. Winter, I. Windemut, N. Kevlishvili, D. Schmeling and J. Maier, Passenger Comfort for the Next Generation Train: Subject Trials for Ventilation and Lighting, in J. Pombo, (Editor), Proceedings of the 3rd International Conference on Railway Technology: Research, Development and Maintenance, Civil-Comp Press, Stirlingshire, UK, 2016. ASHRAE, Thermal guidelines for data processing environments (2nd ed.). Atlanta: American Society of Heating, Refrigerating and Air-Conditioning Engineers, 2009 J. Maier, O. Zierke, H.-J. Hörmann, I. Windemut, Subjectivity of lighting perception and comfort: The role of preferences and expectations, 2016, in prep. C. Marggraf-Micheel, J. Winzen, J. Bosbach, A. Heider, Spitzencluster Luftfahrt - Metropolregion Hamburg - Lichtempfinden und Kabinenklima: Schlussbericht für das Projekt LiKab (Lichtempfinden und Kabinenklima). Hamburg: DLR e.V., 2014 J. Winter, C. Kalatz, Ultra-High-Speed Passenger Train (NGT HST): Conceptual Design of an Innovative Station, paper 202, Proceedings of the 2nd Int. Conf. on Railways Technology, 2014 A. Schumann, G. Kopp, M. Senftleben, K. Krause, Sandwich panels with integrated IR-heating layers for passenger transportation, Euro Hybrid Materials and Structures 2014, April 10-11
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