Effects of heated seat and foot heater on thermal comfort and heater energy consumption in vehicle

Subjective experiments involving 12 different conditions were conducted to investigate the effects of heated seats and foot heaters in vehicles on thermal sensation and thermal comfort. The experimental conditions involved various combinations of the operative temperature in the test room (10 or 20°C), a heated seat (on/off) and a foot heater (room operative temperature?+10 or?+20°C). The heated seat and foot heater improved the occupant's thermal sensation and comfort in cool environments. The room operative temperature at which the occupants felt a 'neutral' overall thermal sensation was decreased by about 3°C by using the heated seat or foot heater and by about 6°C when both devices were used. Moreover, the effects of these devices on vehicle heater energy consumption were investigated using simulations. As a result, it was revealed that heated seats and foot heaters can reduce the total heater energy consumption of vehicles. Statement of Relevance: Subjective experiments were conducted to investigate the effects of heated seats and foot heaters in vehicles on thermal comfort. The heated seat and foot heater improved the occupant's thermal sensation and comfort in cool environments. These devices can reduce the total heater energy consumption in vehicles.     

Effects of heated seats in vehicles on thermal comfort during the initial warm-up period

Eight subjects participated in a subjective experiment of eight conditions to investigate the effects of heated seats in vehicles on skin temperature, thermal sensation and thermal comfort during the initial warm-up period. The experimental conditions were designed as a combination of air temperature in the test room (5, 10, 15, or 20 °C) and heated seat (on/off). The heated seat was effective for improving thermal comfort during the initial warm-up period when air temperature was lower than 15 °C. Use of heated seats prevented decreases in or increased toe skin temperature. Heated seats also increased foot thermal sensation at 15 and 20 °C. Optimal thermal sensation in contact with the seat was higher when air temperature was lower. Optimal skin temperature in contact with the seat back was higher than that with the seat cushion. Moreover, these optimal skin temperatures were higher when air temperature was lower.     

An ergonomics investigation into human thermal comfort using an automobile seat heated with encapsulated carbonized fabric (ECF).

This report presents the results of an ergonomics investigation into human thermal comfort using an automobile seat heated with an encapsulated carbonized fabric (ECF). Subjective and objective thermal comfort data were recorded while participants sat for 90 min in a heated and a non-heated automobile seat in an environmental chamber. Eight male participants each completed eight experimental sessions in a balanced order repeated measures experimental design. The conditions in the chamber were representative of a range of cool vehicle thermal environments (5, 10, 15 and 20 degrees C; in the 20 degrees C trial participants sat beside a 5 degrees C 'cold wall'). Participants in the heated seat condition used the heating controller with separate temperature control over the back of the seat (squab) and bottom of the seat (cushion) in an effort to maintain their thermal comfort while wearing the provided clothing, which had an estimated insulation value of 0.9 Clo. The trials showed that participants' overall sensations remained higher than 'slightly cool' in the heated seat at all temperatures. Participants' overall discomfort remained lower (i.e. more comfortable) than 'slightly uncomfortable' at temperatures ranging down to nearly 5 degrees C in the heated seat. Hand and foot comfort, sensation and temperature were similar in both seats. Asymmetric torso and thigh skin temperatures were higher in the heated seat although no significant discomfort was found in the front and back of the torso and thigh in either seat. Participants reported no significant difference in alertness between the control and heated seat.     

The influence of heated or cooled seats on the acceptable ambient temperature range

In 11 climate chamber experiments at air temperatures ranging from 15 to 45°C, a total of 24 subjects, dressed in appropriate clothing for entering a vehicle at these temperatures, were each exposed to four different seat temperatures, ranging from cool to warm. In one simulated summer series, subjects were preconditioned to be too hot, while in other series they were preconditioned to be thermally neutral. They reported their thermal sensations, overall thermal acceptability and comfort on visual analogue scales at regular intervals. Instantaneous heat flow to the seat was measured continuously. At each ambient room temperature, the percentage dissatisfied was found to be a second-order polynomial function of local heat flow. Zero heat flow was preferred at an air temperature of 22°C and the heat flow that minimized the percentage dissatisfied was found to be a single linear function of air temperature in all conditions. The analysis indicates that providing optimal seat temperature would extend the conventional 80% acceptable range of air temperature for drivers and passengers in vehicle cabins by 9.3°C downwards and by 6.4°C upwards.     

Optimal control of a fuel-fired auxiliary heater for an improved passenger vehicle warm-up

In order to mitigate the comfort problems during a vehicle warm-up, the vehicles propelled by high-efficiency engines are increasingly equipped with auxiliary heaters. Although the usage of an auxiliary heater improves engine efficiency during warm-up, a higher total fuel consumption results in general. In this paper, an optimal, model-based feedback control law for the optimal operation of a fuel-fired heater with respect to passenger comfort and fuel economy is derived. To this end, a control-oriented mathematical model of the system is established, calibrated, and validated. Based on this model, an optimal control problem is formulated and solved. In simulation studies, the functionality of the resulting optimal controller is demonstrated, and its superiority to the state-of-the-art control laws is assessed.     

Future vehicles: the effect of seat configuration on posture and quality of conversation

Abstract

The percentage of passengers that prefer travelling in groups is increasing. In most vehicles, passengers sit side by side and need to turn their body to be engaged in the conversation with their fellow travellers. However, rotating the body could lead to discomfort which influences conversation quality. The aim of this research is to study the effect of seat configuration on the (dis)comfort experience, conversation quality and posture. Experiments in which participants were asked to talk to each other while sitting at the same distance (1 m) were conducted in four seating arrangements (with seat-belts on), where the angle between the forward directions of two seats were positioned at 0° (side by side), 22.5°, 90° and 120° (almost opposite each other), respectively. Optical tracking has been deployed and the collected data were processed with MatLab^® to acquire postural angles over time. Questionnaires were also used to evaluate the perceived (dis)comfort and the quality of the conversation. Experiment results indicate that the 120° configuration scored the best in the overall comfort and the quality of conversation, but only slightly better than the 90° configuration.

Practitioner summary: Seating side by side is not optimal to have a comfortable conversation with your seatmate. To improve comfort and quality of conversation in future vehicles, we tested four seating arrangements analysing the effect of seat layout on (dis)comfort experience. Statistical analysis of objective and subjective data shows the optimal configuration for a comfortable conversation.

Abbreviation: LPD: localized postural discomfort; PDF: probability density function; OCRA: occupational repetitive action     

An on-the-road experiment into the thermal comfort of car seats

This paper presents an evaluation of thermal comfort in an extended road trial study. Automobile seats play an important role in improving the thermal comfort. In the assessment of thermal comfort in autos, in general subjective and objective measurements are used. Testing on the road is very difficult but real traffic conditions affect the comfort level directly, as well as the driver's experience to real conditions. Thus, for such cases real traffic situations should not be neglected in the evaluation of comfort. The aim of this study was to carry out, on an extended road trial study, an evaluation of thermal comfort using human subjects. In the experiments used, the 100% polyester seat cover had three different cover materials, which were velvet, jacquard and micro fiber. All experiments were carried out on a sunny day with ten participants over 1h. They were carried out at air temperatures of 25 degrees C in a Fiat Marea 2004, which had an automatic climate function. Skin temperature at eight points and skin wettedness at two points on the human body were measured during the trials. Participants were required to complete a questionnaire of 15 questions, every 5 min. It can be concluded that there was negligible difference in participants' reported thermal sensation between the three seats. According to objective measurement results, all seat cover materials have the same degree of thermal comfort. On the road the participants feel warmer around their waist than any other area of the body. It was suggested that the effects of real traffic conditions must be accounted for in comfort predictions.     

Driver sitting comfort and discomfort (part I): Use of subjective ratings in discriminating car seats and correspondence among ratings

Several subjective rating schemes were investigated to determine which might be the most effective for use in designing and evaluating car seats, and what relationships exist among these schemes. Participants (n=27) completed short-term driving sessions, in six combinations of seats (from vehicles ranked high and low on overall comfort), vehicle class (sedan and SUV), and driving venue (lab-based and field). Overall ratings were obtained, as well as separate measures of comfort and discomfort of the whole body and local body parts. No association was found between subjective ratings and a publicly available overall vehicle comfort score (J.D. Power and Associates’ Comfort Score), implying that other factors besides sitting comfort/discomfort (and car seats) account for overall vehicle comfort. Other major results were that contemporary car seats appear to best accommodate those of middle stature, that packages/seats of sedans were preferred over those of SUVs, that separate processes appeared to be involved in determining whole body comfort and discomfort, and that ratings of comfort were most effective at differentiating among the car seats. Finally, a scheme for the use of subjective ratings was suggested: discomfort ratings for ensuring basic seat requirements (pain prevention-oriented) and comfort ratings for promoting advanced seat requirements (pleasure promotion-oriented).

Relevance to industry

Evidence regarding the advantages and disadvantages of different subjective rating schemes can facilitate future design and evaluation of automotive seats.     

Micro-hotplate based temperature stabilization system for CMOS SAW resonators

Due to the sensitivity of the piezoelectric layer in surface acoustic wave (SAW) resonators to temperature, a method of achieving device stability as a function of temperature is required. This work presents two methods of temperature control for CMOS SAW resonators using embedded polysilicon heaters. The first approach employs the oven control temperature stabilization scheme. Using this approach, the device’s temperature is elevated using on-chip heaters to T_max = 42°C to maintain constant device temperature. Both DC and RF measurements of the heater together with the resonator were conducted. Experimental results have indicated that the TCF of the CMOS SAW resonator of −97.2 ppm/°C has been reduced to −23.19 ppm/°C when heated to 42°C. The second scheme uses a feedback control circuit to switch the on-chip heaters on and off depending on the ambient temperature. This method provided reduction of the TCF from −165.38 ppm/°C, to −93.33 ppm/°C. Comparison of both methods was also provided.     

MEMS-based microthruster with integrated platinum thin film resistance temperature detector (RTD), heater meander and thermal insulation for operation up to 1,000°C

We have fabricated microthruster chip pairs—one chip with microthruster structures such as injection capillaries, combustion chamber and converging/diverging nozzle machined using the deep reactive ion etching process, the other chip with sputtered platinum (Pt) thin film devices such as resistance temperature detectors (RTDs) and a heater. To our knowledge, this is the first microelectromechanical systems-based microthruster with fully integrated temperature sensors. The effects of anneal up to 1,050°C on the surface morphology of Pt thin films with varied geometry as well as with/without PECVD-SiO₂ coating were investigated in air and N₂ and results will also be presented. It was observed that by reducing the lateral scale of thin films the morphology change can be suppressed and their adhesion on the substrate can be enhanced. Chemical analysis with X-ray photoelectron spectroscopy showed that no diffusion took place between neighboring layers during annealing up to 1?h at 1,050°C in air. Electrical characterization of sensors was carried out between room temperature and 1,000°C with a ramp of ±5?Kmin^?1 in air and N₂. In N₂, the temperature-resistance characteristics of sensors had stabilized to a large extent after the first heating. After stabilization the sensors underwent up to eight further temperature cycles. The maximum drift of the sensor signal was observed for temperatures above 950°C and was less than 8.5?K in N₂. To reduce the loss of combustion heat, chip material around microthruster structures was partially removed with laser ablation. The effects of thermal insulation were investigated with microthruster chip pairs which were clamped together mechanically. The heater was operated with up to 20?W and the temperature distribution in the chip pairs with/without thermal insulation was monitored with seven integrated RTDs. The experiments showed that a thermal insulation allows the maximum temperature as well as the temperature gradient within the microthruster chip pairs to be increased.     

基于ARM的油田单井油罐太阳能加温控制器的设计

为了保证井口输油管道中原油的流动性,针对传统的电加热器和水套炉存在的热效率低、功耗大、不稳定及废气对环境造成污染等问题,提出了一套以太阳能集热器为主、热泵热水器为辅的加热系统。该系统采用温度采集卡实现10路温度信号及6路开关量信号的采集,利用三星的S3C2410 ARM控制器对太阳能集热器和热泵进行交替控制,从而实现储油罐原油的加热控制。触摸屏采用3.5英寸的TFT液晶屏,并将WINCE操作系统移植到ARM处理器,从而实现了良好的人机交互控制界面。     

Thermal comfort of aeroplane seats: influence of different seat materials and the use of laboratory test methods

This study determined the influence of different cover and cushion materials on the thermal comfort of aeroplane seats. Different materials as well as ready made seats were investigated by the physiological laboratory test methods Skin Model and seat comfort tester. Additionally, seat trials with human test subjects were performed in a climatic chamber. Results show that a fabric cover produces a considerably higher sweat transport than leather. A three-dimensional knitted spacer fabric turns out to be the better cushion alternative in comparison to a moulded foam pad. Results from the physiological laboratory test methods nicely correspond to the seat trials with human test subjects.     

Driver sitting comfort and discomfort (part II): Relationships with and prediction from interface pressure

Pressure at the driver–seat interface has been used as an objective method to assess seat design, yet existing evidence regarding its efficacy is mixed. The current study examined associations between three subjective ratings (overall, comfort, and discomfort) and 36 measures describing driver–seat interface pressure, and identified pressure level, contact area, and ratio (local to global) variables that could be effectively used to improve subjective responses. Each of 27 participants was involved in six separate driving sessions which included combinations of two seats (from vehicles ranked high and low on overall comfort), two vehicle classes (sedan and SUV), and two driving venues (lab-based and field). Several pressure variables were identified as more effective for assessing sitting comfort and discomfort across a range of individual statures. Based on the results, specific approaches are recommended to improve the sitting experience: (1) lower pressure ratios at the buttocks and higher pressure ratios at the upper and lower back; and (2) balanced pressure between the bilateral buttocks, and between the lower and upper body. Finally, separate analyses supported that human–seat interface pressure was more strongly related with overall and comfort ratings than with discomfort ratings.

Relevance to industry

Several interface pressure variables were identified that showed associations with subjective responses during sitting. Use of these measures is suggested to improve the quality of car seats.     

The effects of solar radiation and black body re-radiation on thermal comfort

When the sun shines on people in enclosed spaces, such as in buildings or vehicles, it directly affects thermal comfort. There is also an indirect effect as surrounding surfaces are heated exposing a person to re-radiation. This laboratory study investigated the effects of long wave re-radiation on thermal comfort, individually and when combined with direct solar radiation. Nine male participants (26.0 +/- 4.7 years) took part in three experimental sessions where they were exposed to radiation from a hot black panel heated to 100 degrees C; direct simulated solar radiation of 600 Wm(-2) and the combined simulated solar radiation and black panel radiation. Exposures were for 30 min, during which subjective responses and mean skin temperatures were recorded. The results showed that, at a surface temperature of 100 degrees C (close to maximum in practice), radiation from the flat black panel provided thermal discomfort but that this was relatively small when compared with the effects of direct solar radiation. It was concluded that re-radiation, from a dashboard in a vehicle, for example, will not have a major direct influence on thermal comfort and that existing models of thermal comfort do not require a specific modification. These results showed that, for the conditions investigated, the addition of re-radiation from internal components has an effect on thermal sensation when combined with direct solar radiation. However, it is not considered that it will be a major factor in a real world situation. This is because, in practice, dashboards are unlikely to maintain very high surface temperatures in vehicles without an unacceptably high air temperature. This study quantifies the contribution of short- and long-wave radiation to thermal comfort. The results will aid vehicle designers to have a better understanding of the complex radiation environment. These include direct radiation from the sun as well as re-radiation from the dashboard and other internal surfaces.     

The ergonomics of airplane seats: The problem with economy class

The increase in size (body mass and stature) and changing proportions of the human body over the past few decades should be considered in the ergonomic design of economy class airline seats. The aim of this study was to analyze the incongruity of the minimum space for seated passengers considering a group of Spanish adults. Thirteen variables were measured in a group of 201 females and 346 males. The results suggest a minimum leg room between 68.1 and 70.1 cm, and seat width between 50.2 and 52.3 cm. According to this study we can conclude that it is necessary to increase the minimum space in economy airline seats, specifically in terms of leg room and seat width.Relevance to industryThe increase in space of the economy class airline seats in the airline industry can be regarded as an important measure to reduce health risks, and improvement of comfort in the 21st century.     

The influence of heated or cooled seats on the acceptable ambient temperature range

In 11 climate chamber experiments at air temperatures ranging from 15 to 45 degrees C, a total of 24 subjects, dressed in appropriate clothing for entering a vehicle at these temperatures, were each exposed to four different seat temperatures, ranging from cool to warm. In one simulated summer series, subjects were preconditioned to be too hot, while in other series they were preconditioned to be thermally neutral. They reported their thermal sensations, overall thermal acceptability and comfort on visual analogue scales at regular intervals. Instantaneous heat flow to the seat was measured continuously. At each ambient room temperature, the percentage dissatisfied was found to be a second-order polynomial function of local heat flow. Zero heat flow was preferred at an air temperature of 22 degrees C and the heat flow that minimized the percentage dissatisfied was found to be a single linear function of air temperature in all conditions. The analysis indicates that providing optimal seat temperature would extend the conventional 80% acceptable range of air temperature for drivers and passengers in vehicle cabins by 9.3 degrees C downwards and by 6.4 degrees C upwards.     

Study on the effect of heating plate thickness on the micro induction heater for thermal bubbles generation

This paper designed a micro planar induction heater for thermal bubbles generation. The micro heater which consists of a micro planar coil, a copper heating plate and a glass slide was fabricated with MEMS fabrication process. The relations between the heating performance and the thickness of heating plate were studied in the simulation with the software of COMSOL. The experimental system has been built and the experimental tests for thermal bubble generation have been also carried out with the prototype. The process of thermal bubbles generation was recorded by the video camera. The frequency of AC current applied in the experiment is 100 kHz and the heating time of 1 s. The experimental results indicated that the micro heater has the best heating performance with the heating plate thickness of 12–16 μm, and the minimum power for thermal bubbles generation was only 0.427 W. This micro heater can be applied to a variety of thermal bubble devices, such as micro actuator, micro ejector and micro pump.     

Coach design for the Korean high-speed train: a systematic approach to passenger seat design and layout

Proper ergonomic design of a passenger seat and coach layout for a high-speed train is an essential component that is directly related to passenger comfort. In this research, a systematic approach to the design of passenger seats was described and the coach layout which reflected the tradeoff between transportation capacity and passenger comfort was investigated for the Korean high-speed train. As a result, design recommendations and specifications of the passenger seat and its layout were suggested. The whole design process is composed of four stages. A survey and analysis of design requirement was first conducted, which formed the base for designing the first and second class passenger seats. Prototypes were made and evaluated iteratively, and seat arrangement and coach layout were finally obtained. The systematic approach and recommendations suggested in this study are expected to be applicable to the seat design for public transportations and to help modify and redesign existing vehicular seats.     

The effect of 17-inch-wide and 18-inch-wide airplane passenger seats on comfort

The pitch and width of airline seats are crucial factors on the comfort of passengers. The aim of this study is to measure the comfort feeling of passengers regarding different widths and together with data from a previous study, to offer suggestions on the aircraft interior design. 311 participants were recruited and were asked to sit in 17-inch-wide and 18-inch-wide aircraft seats in a Boeing 737 fuselage for 10 min, respectively. Questionnaires on psychological comfort and overall discomfort, as well as an additional questionnaire on the discomfort of different body parts, were used to evaluate the comfort and discomfort experience of participants. Experiment results indicated that the comfort scores were significantly higher, and the discomfort scores were significantly lower for sitting in the 18-inch-wide seats than that of sitting in the 17-inch-wide seats. It was also found that rather than the buttock, the shoulders, knees, lower legs and feet contributed significantly to the reduction in overall discomfort by providing more space for movements. Regarding anthropometric measurements, participants with smaller hip-breadth felt more comfort while sitting the 18-inch-wide seat, which highlights the importance of the freedom of movement. By synthesizing the results of a previous study on the relations of the seat pitch and comfort, it was found that given the same amount of additional floor area, widening the seat is more effective on comfort than increasing the pitch.Relevance to industry: This discovery might be useful for the airline industry for a more effective and efficient usage of floor area.     

Comfort design and optimization of direct expansion multi-connected radiant air conditioning based on 3D flow field simulation

The air conditioning method based on radiation heat exchange has the characteristics of small vertical temperature gradient, high thermal comfort and energy saving, and has become a hot spot of attention. The Fluent numerical simulation, the experiment in this paper studies the direct expansion multi-line radiant air conditioner under the artificially simulated climate environment in winter heating, summer cooling and dehumidification. The temperature difference of the radiation + fresh air mode at the same time indoors under heating conditions is less than 2.5 °C, and the time to reach the indoor set temperature of 24 °C is about 2–3 h. Under cooling conditions, the temperature difference of the radiation + fresh air mode at the same time in the room is about 0.5–2 °C, and the time to reach the indoor set temperature of 26 °C is about 1–3 h. In the fresh air mode, the indoor temperature difference and response time at the same time are slightly larger than the radiation + fresh air mode. The freezing and dehumidification effect of fresh air is obvious, the moisture content of dehumidifying fresh air is between 6.3 and 10.5 g/kg, and the dehumidification efficiency can reach 50%. Under the same artificial simulated climate environment, the consumption of the three modes is not much different. When the outdoor temperature in heating conditions is higher than 9 °C, the fresh air mode can get better, and the radiation + fresh air mode can achieve better comfort when running indoors under various conditions.