Thermal Comfort Of Passengers Research Articles

Analysis of thermal comfort on planes

Thermal comfort of passengers and cabin crew is an important element to be ensured during short and long distance flights. The analysis of this phenomenon is usually conducted based on the measurements of physical parameters of the inside air and factors such as metabolic rate and thermal insulation of clothes. The paper provides an insight into this phenomenon through the literature review on the subject. It presents the assessment of thermal comfort conditions onboard the planes. An important element is the discussion of the current model of thermal comfort proposed by O. Fanger and its usability for the application in planes.

HVAC operation planning for electric bus trips based on chance-constrained programming

Turning on the heating, ventilation and air-conditioning (HVAC) system is one effective measure to improve the thermal comfort of passengers in an electric bus (EB). However, it will also increase the consumption of the battery power. For an EB with limited battery capacity and that can only be charged at night, it is impossible to keep the HVAC on for all-day trips. This study aims to develop a daily HVAC operation planning model for an EB to maximize the thermal comfort of the passengers under the constraint of battery capacity. Firstly, we developed a cabin temperature estimation model to quantify the thermal comfort of the passengers. Secondly, considering the stochastic volatility of trip energy consumption, the chance-constrained programming based HVAC planning model is established, to determine the optimal HVAC gear of each trip. Finally, a real EB is taken as an example and field operational data collected in three different seasons are used in the case study. Results show that passenger's thermal comfort can be improved in different seasons after applying the proposed optimization method while avoiding the service interruption due to running down of battery power.

Investigation on thermal environment of subway stations in severe cold region of China: A case study in Harbin

In recent years, numerous subway lines have been under construction with the rapid development of subways in the cold regions of China. Harbin, a typical city in severe cold regions, has harsh winter weather, and the lowest outdoor temperature can reach −37.7 °C. Therefore, the thermal environment of the station and the thermal comfort of passengers are facing huge challenges. Owing to the complexity of the subway environment, few field test studies, especially long-term tests, have been conducted. In this study, long-term field test on the thermal environment, questionnaire survey and thermal comfort analysis of two typical subway stations were conducted. A revised comfort temperature was proposed based on the constant changes in passenger metabolism. The field test results showed that the temperature and moisture content of the station were affected by the type of platform door, interval driving, operating time, and piston effect. The results of the questionnaire survey showed that the temperature, humidity, and thermal comfort of the two subway stations were satisfactory for most passengers. Passengers experienced a noticeable draft only in the aisle. After calculation, the lower limits of the comfortable temperature for the aisle, hall, and platform of the Harbin Metro were determined to be 10.6, 11.2, and 13.8 °C, respectively. The data obtained in this study provide a valuable reference for the construction and operation of subways in severe cold regions.

A novel method to investigate the influence of phase change material orientation in reduction of car cabin temperature

Car parked in peak sun light, attains temperature higher than the surroundings. Due to this, the passenger develops discomfort while entering into the car. For the betterment of passenger's thermal comfort, the phase change material (PCM) is employed inside the car. There were many experiments & numerical studies carried out to find the effect of cabin air temperature by placing the phase change material near the roof and also by varying the melting temperature of phase change material. From the understanding obtained from the literature study, the effect of changing the phase change material orientation with respect to the air flow inside the car cabin is not much reported. In this study, a novel method named equivalent specific heat method has been developed. It is conventional to employ 2 phase simulation for phase change material. By employing this novel method, the computational time associated with the 2 phase simulation is drastically reduced as the entire simulation can be carried out as a single phase. The effect of employing different phase change material and their orientation on reducing the car cabin temperature has been studied in detail. 2 phase change material namely OM29 and HS24 along with their 7 orientations have been investigated. Results in terms of the solar load distribution, the temperature distribution due to solar load, air temperature contours, air velocity contours and phase change material temperature contours have been presented and discussed in detail. It is found that the performance of 2 curvatures of PCM (HS24) covering the roof is able to reduce the average car cabin temperature by 10.4 °C when compared to that without PCM. The reduction in average car cabin temperature is found to be 9.5 °C, 9.1 °C, 7.9 °C, 7.2 °C, 4.7 °C and 4.3 °C for 3 curvatures of PCM (HS24), 1 curvature of PCM (HS24), 2 curvatures of PCM (OM29), 1 curvature of PCM (OM29), Flat PCM (OM29) covering the roof and & Flat PCM (OM29) partially covering the roof respectively. This novel method is capable of reducing the computational time for two phase simulation by 90%. The average deviation for the novel single phase simulation and conventional two phase simulation with that of the experiment is found to be 11.38% and 9.93% respectively.

CFD analysis of rotating diffuser in a SUV vehicle for improving thermal comfort

Nowadays, most of the cars have air conditioning as a standard feature, which improves comfort and safety. Automatic temperature control, incorporated cooling, warming, de-misting and de-frosting, air filtration, humidity management, and safety are all characteristics of modern systems. The interior cabin temperature has the greatest impact on passenger thermal comfort. Cabin temperature is to determine by the size of the cabin, the quantity and form of air vents, the overall HVAC system's mass flow rate, and the dashboard, trimmings, and seating materials. The vanes are adjusted manually to establish the airflow direction and in few, it is automatically adjusted. The round-shaped set-up in the cabin's HVAC system has a dynamic mechanism that is mean to spin at a constant speed along its axis. In this work, SUV vehicle cabin has investigated with different speed and find the suitable temperature range. It should be test using CFD software and steady state thermal analysis. According to ANSYS FLUENT, the observed cabin findings include a temperature of roughly 23 °C and an airflow velocity of 5 m/sec.

Field studies on thermal comfort of passengers in airport terminals and high-speed railway stations in summer

In transportation buildings such as airport terminals and railway stations, the thermal comfort of passengers is associated with the energy consumption of HVAC systems. Previous studies did not reach consistent conclusions on the differences in thermal comfort demands of passengers with different dwell times in waiting halls. In addition, the thermal comfort of passengers in various sessions during the departure and arrival processes, such as security checks and walking, was not addressed. Therefore, we conducted field studies in the waiting halls of ten transportation buildings and 12 simulated experiments of departure and arrival processes in five of these terminals, with 10 subjects in each experiment. A total of 1,576 valid questionnaires were collected from the waiting halls. The results showed that passengers were more adaptable to the indoor thermal environment than the results foreseen by the PMV–PPD model. As the dwell time increased, the adaptability of the passengers to the indoor thermal environment was approximately the same. However, the neutral standard effective temperature (SET) and preferred SET increased with time. The current indoor thermal design parameters of GB 50736 can meet passengers’ thermal comfort during short-distance departure and arrival processes. Under low air velocity conditions (< 0.2 m/s), the 90% acceptable indoor operative temperature (Top) ranged from 21.9 °C to 25.4 °C for the security check and from 23.9 °C to 25.2 °C for the long-distance processes.

Energy audit and evaluation of indoor environment condition inside Assiut International Airport terminal building, Egypt

Large space buildings, such as airport terminal buildings, consume high energy due to the cooling demand; especially in hot arid climates; to achieve passenger thermal comfort. Evaluation of thermal environment and energy analysis inside airports is an important issue, in terms of reducing energy and controlling indoor environments. This work aims to analyze electrical energy consumption and the indoor environment of the terminal building at Assiut International Airport, Egypt as a case study. Indoor environmental conditions, and energy consumption with HVAC systems, were monitored inside five multiple functional zones within the terminal building (Departure hall, Public area, Duty-free hall, Gate, and Arrival hall) during summer (August 2017). The indoor environmental parameters monitored include: temperature, relative humidity, and illuminance. The results indicate the HVAC system consumed the largest portion (70%) of the overall building electricity demand, and the Energy Use Intensity (EUI) of ATZ terminal building is 300 kWh/m 2 /year. Also, indoor temperatures were found to be within the acceptable range of comfort, with a high energy consumption of 6,000,000 kWh for the year 2017. A significant reduction of monthly energy consumption was achieved based on increasing HVAC set temperature from 25 °C to 27 °C; a reduction equal to 24.5% of total energy consumption during the hot months. The results of this study help search for sustainable solutions for reducing energy consumption and improving passenger thermal comfort inside the terminal building (phase 2).

Field investigation on thermal comfort of passengers in an airport terminal in the severe cold zone of China

Numerous airport terminals are being constructed in China. However, the current Chinese standards do not specify an indoor comfort zone for airport terminals. Therefore, this study aims to understand the thermal comfort demand of passengers and provide references for designing an indoor thermal environment in airport terminals. We selected typical periods in May 2019, August 2019, and January 2020 to conduct a thermal comfort field study in an airport terminal in the severe cold zone of China. 640 valid questionnaires were collected in the departure lounge during different seasons, and 625 valid questionnaires from different functional zones during winter were analysed. The neutral Top of passengers was 25.6 °C, 23.7 °C, and 17.7 °C in the departure lounge in summer, transition season, and winter, respectively. The 80% and 90% acceptability ranges of passengers in the departure lounge in transition season and winter were wider than in summer, indicating that passengers were easily adaptable to the indoor environment. Differences are observed in the thermal comfort demands of passengers with different dwell times. Because of the difference in metabolic rates, the preferred temperature in the baggage reclaim (16.2 °C) was lower than in the check-in hall and departure lounge (20.3 °C and 20.7 °C, respectively) during winter. This indicates that different design parameters should be developed according to the characteristics of the metabolic rate and dwell time in different functional zones. The findings from this study show excellent energy-saving potential in airport terminals in winter.

Energy Consumption and CO2 Emissions of Coach Stations in China

As a critical transportation infrastructure, with a high flow of people and high-energy consumption in China, coach stations have great potential in energy saving and CO2 emission reduction. In this paper, the building information and energy consumption data of 29 coach stations in five climate regions of China were obtained by field investigations. The annual total comprehensive building energy consumption was 31.37–128.08 kWh/(m2·a). The annual total CO2 emissions from building operation in the coach stations was 17.01–134.77 kgCO2/(m2·a). The heating, ventilation and air conditioning (HVAC) system was the largest energy using and CO2 emissions sector: 30.42–72.47% of the energy consumption and 30.42–83.93% of the CO2 emissions were generated by HVAC system. The energy consumption and CO2 emission level of coach stations and that of other kinds of public buildings were compared. Results showed that the energy consumption and CO2 emission levels of coach stations investigated were relatively low, mainly because the passenger thermal comfort was scarified. Based on the investigation data, energy consumption analysis models of coach stations in five regions were established by simulation when the passenger thermal comfort was met. The potentials of energy saving and CO2 emission reduction were studied from forms of the HVAC system, heat recovery and natural illumination.

Investigation of Thermal Sensation in a Railway Vehicle during Cooling Period

The paper presents an investigation of local thermal comfort of passengers in a railway vehicle. The railway vehicle model includes five different parts called modules, and each module had different properties such as passenger capacity and seating arrangement. A virtual manikin model was developed and added to the numerical model which includes convection and radiation heat transfer between the human body and the environment. The numerical simulation was conducted according to the EN 14750-1 standard describing the thermal comfort conditions for different climatic zones. Two different cases were performed for steady-state conditions. Meanwhile, measurements were taken in a railway vehicle cabin to validate the numerical simulation, and the numerical results were in good agreement with the experimental data. It is observed that the local heat transfer characteristics of the human body have significant importance for the design of an effective heating, ventilation, and air conditioning (HVAC) system because each module had different heat transfer and air flow characteristics. It is also shown that the thermal sensation (TSENS) index helps railway vehicle HVAC researchers to determine the reasons for discomfort zones of each occupant. Another important result is that using a single air flow channel did not meet the thermal comfort demands of all passengers in this railway vehicle. Therefore, multiple air flow channel design configurations should be considered and developed for these vehicles. Local thermal comfort models allow HVAC systems to achieve better comfort conditions with energy saving. The numerical model can be used for effective module design, including seating arrangements, to achieve better thermal comfort conditions.

Control trajectory optimisation and optimal control of an electric vehicle HVAC system for favourable efficiency and thermal comfort

In order to increase the driving range of battery electric vehicles, while maintaining a high level of thermal comfort inside the passenger cabin, it is necessary to design an energy management system which optimally synthesizes multiple control actions of heating, ventilation and air-conditioning (HVAC) system. To gain an insight into optimal control actions and set a control benchmark, the paper first proposes an algorithm of dynamic programming (DP)-based optimisation of HVAC control variables, which minimises the conflicting criteria of passenger thermal comfort and HVAC efficiency. Next, a hierarchical structure of thermal comfort control system is proposed, which consists of optimised low-level feedback controllers, optimisation-based control allocation algorithm that sets references for the low-level controllers, and a superimposed cabin temperature controller that commands the cooling capacity to the allocation algorithm. Finally, the overall control system is verified by simulation for cool-down scenario, and the simulation results are compared with the DP benchmark. The results show that the control system behaviour can approach the DP benchmark if the superimposed controller bandwidth is tuned along with the allocation cost function weighting coefficients, where a fast controller tuning relates to better thermal comfort while a slow tuning results in improved efficiency.

Thermodynamic Characteristics and Order Degree of Air Cycle System

Abstract An air cycle system (ACS) is the most widely used aircraft environmental control system; it plays an important role in guaranteeing the physical health and thermal comfort of passengers in the cabin. Moreover, an ACS has a considerable impact on the fuel consumption of the aircraft. There is a lack of existing research on the analysis of the operating mechanism of environmental control system. Accordingly, in our study, the thermodynamic characteristics and order degree of the ACS are analyzed based on the endoreversible thermodynamic analysis method (ETM) and the structure entropy method (SEM). Analytic solutions are derived for the thermodynamic characteristics of two types of four-wheel ACSs with high pressure water separation, replacing the complex iteration process in system modelling with algebraic expressions. The correctness of ETM is verified by experimental data. Simultaneously, the order degrees of the two systems are calculated from the perspective of timeliness and quality of information transmission. The results show that the order degree of the split four-wheel ACS is slightly lower than that of the integrated four-wheel ACS, owing to an increase in the uncertainties of the information transmission process. Ultimately, both ETM and SEM are able to provide the theoretical basis for air cycle system design, assessment, and selection.

Impact of elevated outdoor MRT station towards passenger thermal comfort: A case study in Jakarta MRT

Comfort of the train passengers is the main priority of modern mass rapid transit (MRT) management. Objective of this paper is to investigate the thermal comfort of the elevated MRT station in tropical climate. The first step of this study was to conduct literature review on human thermal comfort, environment ergonomics, computational fluid dynamic (CFD), computational aeroacoustics (CAA), and predicted mean vote (PMV). Air quality in elevated MRT station was measured based on several parameters: relative humidity, wind speed, temperature, and wind direction. A 3D model of MRT designed was used to describe existing condition prior to simulations with CFD and CAA softwares. Predicted mean vote is arranged based on the value of metabolism, wind speed, ambient temperature, mean radiant temperature, amount of insulation from clothing, and relative humidity. Whereas predicted percentage of dissatisfi ed (PPD) can be derived from PMV calculations. The analysis shows that the average PMV of existing condition for elevated outdoor MRT station is 3.6 (extremely hot) with PPD is 100% (all passengers felt discomfort). Some recommendations to reduce heat stress were addressed such as: adding plant, changing materials of the MRT station, and change the design of the elevated MRT station. Modifying open elevated MRT station into indoor elevated MRT station with installing six units of AC (2pk, ±23°C) can improve air quality and maintain the thermal comfort scale of PMV to be –0.04 (comfort) with PPD of &lt; 8%. Based on the analysis, it can be concluded that the most suitable design for elevated MRT station in tropical climate (hot and humid) is indoor MRT station with pay attention to both direct and indirect heat exposure that hit the station.

Indoor air quality and passenger thermal comfort in Beijing metro transfer stations

In this study, particulate matter was investigated as the primary pollutant in the air quality of Beijing Metro transfer stations, and passenger thermal comfort during the transfer process was evaluated by using the relative warmth index (RWI). Passenger thermal comfort level is not ideal in 87% of the measured space and is slightly hot overall, with an RWI range of 0.20–0.43. Although 20% of the measured space has lower values than ASHRAE’s cooling comfort class, the thermal comfort level of most measured space is good in winter morning rush hours, with an RWI range from −0.18 to 0.28. The particulate matter (PM) concentration is related not only to the season and spatial depth but also to the transfer design of the metro station. During the morning rush period, the concentration ranges difference of PM10 and PM2.5 in winter are 262.9 μg/m3 and 125.5 μg/m3, respectively, which are 1.43 and 1.46 times higher than those of in summer. There are significant differences in the PM concentration and RWI values between the island and lateral platforms of Beijing Metro transfer stations, and the design of the lateral platform is superior to that of the island platform. Another exploratory experiment is conducted to determine if the PM concentration has a potential effect on human metabolic rate. The data in this paper provide a valuable reference for further comfort research and environmental control in metro station, and the conclusions may guide the further underground space design of metro transfer stations.

Application of scaling-endoreversible thermodynamic analysis model to aircraft environmental control system-methodology development

An Aircraft environmental control system (ECS) is a complex thermodynamic system that ensures the health and thermal comfort of passengers. The investigation of the thermodynamic characteristics of the ECS helps improve the energy efficiency of aircraft. Existing research focuses on the optimization analysis of thermodynamic processes. In this study, to obtain the analytical solution of the thermodynamic characteristics of the ECS, a scaling-endoreversible thermodynamic analysis model (SETM) is proposed and applied to a two-wheel bootstrap air cycle system with high-pressure water separation. Results show that the maximum average error between theoretical results and experimental results is 1.82% after humidity correction. In addition, the effectiveness of a heat exchanger significantly affects the coefficient of performance of the ECS and it can be estimated under different inlet parameters using the heat exchanger scaling model. This helps in predicting system thermal performance more accurately.

Modelling of the predicted thermal comfort of the metro passengers under different crowd densities

The aim of this study is to find out the nature of the metro passenger's thermal comfort under different crowd densities and different ambient environment factors. Taking the human factors, garment factors and ambient environmental factors into consideration, a sub-model human thermal perception was investigated based on the Fanger's heat balance equation. Also, a steady thermal sub-model of the B-type metro vehicle was built based on the heat conservation among the passengers, the outside-vehicle environment and the air of human-vehicle system. Then, the human thermal perception and its alternation were quantified by applying the PMV index. Simulation results show that the passenger's thermal perception cannot only variates with the airflow velocity, the relative humidity and the volume of the new air, but also with the crowd density.

Sound proofing and thermal properties of an innovative viscoelastic treatment for the turboprop aircraft fuselage

Low-resilience polyurethane foams including several additive constituents were synthesized to improve their vibro-acoustic performances, as well as the thermal insulation. viscoelastic polymer additive can attenuate vibrations and absorb sound energy. the vibro-acoustic properties of two innovative viscoelastic treatments fabricated with polyurethane foams are discussed in this paper using a typical aeronautical panel test setup. Since an aircraft insulation arrangement must provide both noise and thermal insulation for the specified operating conditions and expected thermal comfort of passengers, the thermal conductivity of the samples has been examined assuming a testing range between 20 °C (room temperature) and − 40 °C (cruise altitude). the results highlighted an optimal behavior of the novel viscoelastic foams in terms of both acoustic and thermal performance, offering a very interesting self-embedded solution with a good weight to performance ratio, compared to standard blanket composed by extra viscoelastic treatments.

Improving the Performance Attributes of Plug-in Hybrid Electric Vehicles in Hot Climates through Key-Off Battery Cooling

Ambient conditions can have a significant impact on the average and maximum temperature of the battery of electric and plug-in hybrid electric vehicles. Given the sensitivity of the ageing mechanisms of typical battery cells to temperature, a significant variability in battery lifetime has been reported with geographical location. In addition, high battery temperature and the associated cooling requirements can cause poor passenger thermal comfort, while extreme battery temperatures can negatively impact the power output of the battery, limiting the available electric traction torque. Avoiding such issues requires enabling battery cooling even when the vehicle is parked and not plugged in (key-off), but the associated extra energy requirements make applying key-off cooling a non-trivial decision. In this paper, a representative plug-in parallel hybrid electric vehicle model is used to simulate a typical 24-h duty cycle to quantify the impact of hot ambient conditions on three performance attributes of the vehicle: the battery lifetime, passenger thermal comfort and fuel economy. Key-off cooling is defined as an optimal control problem in view of the duty cycle of the vehicle. The problem is then solved using the dynamic programming method. Controlling key-off cooling through this method leads to significant improvements in the battery lifetime, while benefiting the fuel economy and thermal comfort attributes. To further improve the battery lifetime, partial charging of the battery is considered. An algorithm is developed that determines the optimum combination of key-off cooling and the level of battery charge. Simulation results confirm the benefits of the proposed method.

Field study on thermal comfort of passenger at high-speed railway station in transition season

Previous studies on thermal comfort have been mainly conducted in climate chamber, summer and winter in air-conditioned buildings and summer in naturally ventilated buildings, but rarely in transition season (non-air conditioned environment) in air-conditioned buildings. For buildings with large space and high density of people like in high-speed rail station, the thermal comfort of passengers in waiting room in non-air conditioned condition should be a concern. According to ISO 7730 and ASHRAE 55, field studies have been carried out in two high-speed railway stations during late spring and late fall in Shandong and Hebei, two provinces located in the cold region of China, using a subjective questionnaire survey simultaneously with thermal environmental parameter monitoring.As a result, the neutral temperature of the passenger was revealed, and the thermal acceptability and preference are discussed. In addition, a suitable model to predict the thermal comfort of the passenger in transition season was developed. Ultimately, we studied the relationship between the length of the waiting time and the thermal comfort of the passengers.

Effects of air supply diffusers and air return grilles layout on contaminants concentration in bus passenger compartment

Ventilation system in a bus is employed to provide good indoor air quality and thermal comfort for passengers. Poor ventilation system will increase the concentration level of air contaminants which could affect the passenger’s health. The presence mixing ventilation system used in many buses is not efficient in removing the air contaminants from the passenger compartments. This article presents a study on the effects of using different ventilation setups on the concentration level of gases and particulate matters inside a passenger compartment of a university’s shuttle bus. The goal is to find a suitable layout of the air supply diffusers and air return grilles that would lower the concentration level of contaminants inside the passenger compartment. Field measurements were carried out to quantify the concentration of gases (carbon monoxide, carbon dioxide and formaldehyde) and particulate matters (PM1, PM2.5 and PM10). The measurements were done at the front section of the bus compartment, close to the front door. The data were acquired in the morning, afternoon and evening hours during a clear and sunny day. The bus travelled along an in-campus road with no passengers. A simplified three-dimensional model of the bus compartment was developed using computational fluid dynamics software. Flow analyses were carried out to predict distribution of gases and particulate matters concentration. The concentrations of carbon dioxide, carbon monoxide, formaldehyde and particulate matters obtained from the field measurements were used as boundary conditions and for validating the computational model. A parametric study was carried out to identify a suitable layout of air supply diffusers and air return grilles that would lower the concentration level of the air contaminants. Two types of ventilation systems were considered namely a displacement ventilation and an underfloor air distribution. Results show that the underfloor air distribution system is more effective in reducing the concentration level of gases and particulate matters inside the passenger compartment compared to the displacement ventilation system.