Thermal Comfort Research Articles

Comparison of Indoor Climate between Wooden wall Construction and Concrete Wall Construction during Winter Season

Abstract This research aims to determine the importance of thermal comfort in buildings, especially residential houses, with a focus on two types of houses that have different structures as a comparison. The research also focuses on productive rooms that are frequently used every day, considering the long duration of use. Data collection methods include distributing questionnaires to residents, as well as a quantitative approach using experiments and thermal measurements of temperature and humidity in each room, including surface measurements to compare the two types of buildings. The analysis results show that there are differences in thermal comfort between the two types of houses. Houses with wooden construction show relative humidity that reaches a comfortable point (45-65%), while houses with concrete construction tend to move cold temperatures from outside to indoors more quickly. Although efforts have been made to achieve thermal comfort in every room, the main challenge remains related to the energy consumption of artificial comfort systems. The study location in Japan took into account the different outdoor temperature variations each season. The findings we got were that houses with wooden construction walls tend to be warmer due to several factors, one of which is that this building is an apartment type with openings that tend to be smaller compared to buildings with wooden construction walls which are a traditional Japanese house type with wide openings. The measurement results using PMV analysis for both buildings were measured at 2 times at the same time, namely during the day and at night. Measurements were carried out in the living room as a comparison room with the function of a room that has the same user interaction between the two buildings. Honjo Nishi Danci Apartment (concrete wall construction) has a comfort level in the quite comfortable category compared to the living room in the apartment. Kitakyushu Islamic Cultural Center (wooden wall construction). Data was taken when both buildings did not turn on the air conditioner so that the data taken could be comparable. At night, the conditions in the living room have a slightly warm sensation because the user uses air conditioning in the room because the user sleeps in this room. the conditions in the living room at the Islamic Cultural Center have a cold sensation due to the lack of activity and use of this room. So the sensation at night tends to be cold. These findings can guide building designers in developing architectural solutions that are sustainable and focused on indoor comfort in winter.

Park thermal comfort and cooling mechanisms in present and future climate scenarios

Extreme heat is Australia’s most perilous natural hazard, and increasing urban temperatures due to climate change are a growing concern. Consequently, there is growing interest in developing nature-based solutions (i.e., greenery and vegetated surfaces) to cool urban areas. Appropriately designed urban parks are anticipated to be crucial for maintaining thermal comfort as temperatures rise. The two main diurnal cooling mechanisms of urban parks are shade provision and vegetation transpiration. However, limited studies have examined the cooling performance of vegetation through transpiration, especially in the southern hemisphere. This study addresses this gap by examining the microclimatic conditions, cooling benefits, and thermal performance of a typical neighbourhood park in Perth, Western Australia, with a focus on the cooling performance of vegetation through shade and transpiration. Present and future microclimates were modelled and simulated for average and hottest summer days based on 25 years of local weather data and projections for 2090 under the Representative Concentration Pathway (RCP) 8.5 scenario. The findings reveal that trees provided diurnal cooling benefits for park users by lowering the Universal Thermal Comfort Index (UTCI) by up to 17°C, with this benefit persisting in projected 2090 conditions. This cooling benefit was predominantly achieved through shade provision, with marginal contributions from transpiration. Additionally, on hot days, as leaf temperature exceeded 30°C, increased stomatal resistance led to reduced transpiration. Therefore, more attention must be paid to transpiration cooling limits due to stomatal closure during hot hours to improve cooling performance in park design. Moreover, comparing different plant species’ behaviour and adaptability on hot days is crucial, especially in future climatic conditions.

Improved understanding of thermal comfort could yield energy savings in heritage buildings

Abstract It is necessary to improve the understanding of thermal comfort to reduce energy consumption for heating and cooling in heritage buildings, which are often energy inefficient and where interventions are limited. Personal thermal comfort models based on measurements of environmental conditions and the individual’s physiological and subjective responses represent a potential solution to ensure the optimization of existing systems. Past research shows that lighting could impact thermophysiology and subjective perception of thermal conditions, but it is not clear whether the impact is sufficient to make light adaptation an appropriate solution to reduce energy consumption in heritage buildings, where people live and work. The research conducted under realistic semi-controlled conditions in an office environment of an existing building addresses this research gap. The paper presents the first partial simplified analyses and preliminary results of a wider ongoing study, mainly showing a correlation between skin temperature and air temperature and a partially promising effect of light on subjective thermal perception. Our research on the effect of light on thermal comfort does not provide definitive conclusions but rather highlights the need for further investigation in actual heritage buildings.

Approach on enhancing the air conditioning system to improve the winter thermal environment in Eastern China Region's airport terminals

Passengers typically spend much time in commercial zones of terminals for retail, meals, and other services. Enhancing the study of thermal comfort in this local space is necessary. The climate in the Eastern China Region is variable and complex, making it more challenging to maintain the indoor thermal environment. This study conducted field measurements in winter in a commercial zone of one terminal to assess the thermal environment. Numerical simulations and PMV-PPD analyses were performed using the Computational Fluid Dynamics (CFD) program The results showed that the overall humidity in the commercial zone was low. There were notable differences in the temperatures and velocities of supply air among different air vents on the commercial island. Based on these initial conditions obtained by measurements, the simulations showed that localized areas under the breathing plane are either too hot (24°C and above) or too cold (18°C and below). The dissatisfaction percentage of the population exceeds 27%. This paper proposed that through enhancements in the air vent dimensions, layout, and air supply conditions, the temperature can be maintained in the range of 20-24°C. Furthermore, the PMV could be controlled within the range of -0.5 to 0.5. PPD was below 10%, reflecting compliance with Class I heating standards. Overall, findings from this study provide a less costly modification for thermal comfort improvement in commercial zones, and serve as a reference for the design and operation of air-conditioning systems to ensure thermal comfort in airport terminals’ commercial zones.

Evaluation of pedestrian thermal comfort from a whole-trip perspective: An outdoor empirical study

Pedestrian thermal comfort is a critical factor influencing urban livability and sustainability. However, existing models often overlook its cumulative impact from dynamic thermal experiences throughout the whole-trip. This study builds on previous findings, conducting outdoor mobile observations in Guangzhou's urban blocks on clear summer days. Methods for assessing thermal comfort during pedestrian travel were tested and refined, taking into account participants' skin temperatures and accumulated heat storage. The research found that the dynamic changes and non-uniform distribution of radiant temperature are the main characteristics of pedestrians' thermal experiences during summer clear weather and are critical factors affecting their thermal comfort. Non-uniform exposure to direct solar radiation can cause variations in pedestrians' instantaneous thermal sensations, and dynamic thermal experiences can lead to the formation of memorized thermal sensations, causing a deviation between instantaneous and whole-trip thermal sensations. There is a significant correlation between pedestrians' mean skin temperature and heat storage and their thermal experiences over the past 10–25 min. Regression analysis provided different weights that could represent the memory component in whole-trip thermal sensations. The findings provide a theoretical basis for understanding pedestrian thermal comfort in dynamic outdoor environments and will help improve the thermal quality of outdoor travel spaces.

Research on low energy joint optimization of dynamic thermal environment coupled with passenger cabin and air conditioning systems

This study establishes a model for the coupling of passenger compartment and air-conditioning systems. The model takes human thermal comfort as the evaluation index, which can achieve dynamic data exchange during the transient calculation process, and control the air-conditioning systems with the core goal of reducing energy consumption. The optimal air supply angle and air distribution ratio were analyzed using this model. When the external environment changes, the air supply parameters corresponding to the lowest energy consumption are analyzed based on the air conditioning system with optimal air supply angle and air distribution ratio. The results show that the best direct blowing position is the neck. When the air distribution ratio of the driver's left air outlet is 25 %, the overall thermal comfort value of the dummy is the best. The overall thermal comfort of the dummy was maintained at the optimal value with an air speed of 8 m/s for dynamic external environments, but this air speed was not the lowest energy consumption. Subsequently, under the premise of maintaining the comfort of the dummy, the fitted curves of the air supply speed that minimizes the energy consumption are obtained by comparing the energy consumption under different air supply speeds.

Enhancing the effectiveness of heat adaptation strategies through citizen science-based outdoor thermal comfort

Urbanization and intensifying climate change expose populations in cities to escalating heat stress and associated health risks. Mitigating these challenges require comprehensive assessments that combine quantitative and qualitative data to develop effective heat wave response strategies and policies. Previous research has primarily focused on thermal sensation measured by individual biometrics within specific locations. However, limitations in data collection across large areas often lead to the neglect of the influence of diverse urban environments. This may disregard the importance of regional variations and citizen engagement in formulating effective heat wave mitigation strategies. This study explored the impact of heat wave frequency and intensity across various urban spatial types and assessed thermal sensation vote (TSV) among residents of Suwon City using a citizen science approach. Temperature measurements and subjective heat sensations were collected over a three-year period using homemade temperature sensors. The analysis investigated thermal sensation differences across spatial types—open high rise, open low rise, compact mid-rise, urban park, and lake park—utilizing boxplots, and examined TSV variations by age using the R program localized smoothing methodology. Results indicate significant variations in TSV across different urban areas, particularly when temperatures exceeded 32 °C. The TSV was highest in the lake park areas (average thermal sensation vote +3.5) and was comparatively lower in the open high-rise and open low-rise areas (average thermal sensation vote +2.0). A significant age-related trend was observed, with the highest TSV reported by the 19–30 age group. Heat sensitivity appeared to decrease among participants aged 41 and over. These findings highlight the limitations of traditional top-down heatwave response strategies, which may not adequately account for spatial variations and individual experiences. Conversely, a bottom-up approach that leverages citizen science can inform the development of tailored and proactive strategies that consider a region's specific conditions.

Impact of employing phase change material in building wall on energy consumption and thermal comfort level

Energy crises are becoming a problem for many, most of the energy being produced is utilized in buildings. Building design and materials that are used in buildings play a vital role in saving electricity. Sustainable cities are one of the eleventh goal of Sustainable Development Goals to be achieved and this study is in context of SDGs for developing tools to create this globe sustainable and efficient society for humans. Phase change material is a type of material that can absorb and release heat energy as it changes between solid and liquid states. This ability to store and release thermal energy makes PCM a promising material for use in building insulation, Heating Ventilation Air Conditioning Systems, and other energy efficient applications. The use of PCM in buildings has the potential to significantly reduce energy consumption and improve thermal comfort levels. By incorporating PCM into building envelopes, such as walls, roofs, and floors, the material can absorb excess heat during the day and release it at night, helping to regulate indoor temperatures and reduce the need for heating and cooling systems. This study investigates the impact of using PCM in building envelopes. In this regard office building rooms are modelled in CAD software and are simulated in energy plus software. The simulation results are validated by considering the experiment and numerical study as a reference from paper. Model room is simulated for Hyderabad, Pakistan. Building envelopes without PCM have conduction rate of around 106.6 W/m2, whereas building envelopes with PCM have conduction rate around 42 W/m2. This shows that utilization of PCM reduced heat conduction up to around 40%. PCM reduced energy consumption of around 33.25 kWh/year/m2. Results show that without PCM air temperature was above the thermal comfort value. it reached 300C in hot months, it reduced up to 270C with the incorporation of PCM.

Evaluating and enhancing the applicability of thermal comfort indices in diverse outdoor environments using Bayesian and random forest regression

This research aims to evaluate and improve the applicability of three commonly utilized thermal comfort indices—standard effective temperature (SET), physiological equivalent temperature (PET), and universal thermal climate index (UTCI)—in outdoor environments. The study was conducted in four typical spaces of a university in Xi’an, China, covering different environmental settings: East Lake (Place 1), tree-lined path (Place 2), campus playground (Place 3), and campus square (Place 4). A total of 322 volunteers participated by completing a subjective sensory questionnaire in randomized environments, and on-place meteorological data were collected. The study yielded three primary findings. First, the tree-lined path (Place 2) was identified as the most comfortable outdoor space on the university campus during summer, whereas East Lake (Place 1) was the least comfortable. Second, substantial residuals were observed for SET, PET, and UTCI across different places when assessing the thermal comfort variations experienced by the subjects. Third, Bayesian regression and random forest regression were employed to analyze and adjust the thermal comfort indices. The comparative study found that after correction, the model explanatory power of PET increased by up to 20%, with the standard deviation of residuals decreasing by up to 0.314 and MSE decreasing by up to 0.1912. The model explanatory power of SET increased by up to 31.2%, with the standard deviation of residuals decreasing by up to 0.3867 and MSE decreasing by up to 0.3012. For UTCI, the model explanatory power increased by up to 10.5%, the standard deviation of residuals decreased by up to 0.2215, and the MSE decreased by up to 0.1002.

Research and thermal comfort analysis of the air conditioning system of the Ferris wheel car based on thermoelectric cooling

To solve the problem of thermal discomfort caused by the lack of cooling facilities on the Ferris wheel and to investigate the effect of the coupling effect of thermoelectric modules on the thermoelectric cooling (TEC) system, this paper proposes a two-module thermoelectric cooling and air-conditioning system that can be applied to the Ferris wheel. Firstly, the experimental platform was established to test the performance parameters of the TEC system and reveal the influence of the thermoelectric module (TEM) coupling effect on the system performance. Then, the thermal environment inside the Ferris wheel was simulated using the CFD method and human thermal comfort was evaluated. The results show that when the voltage of TEM1 and TEM2 is 10V and 6V respectively, the thermoelectric cooling and air-conditioning system has the best working performance, and the coefficient of performance (COP) is 0.43. And the human thermal comfort deviation AEQT is 0.29, which is in a comfortable state under the action of the air-conditioning system.

Thermal request optimization of a smart district heating system

This paper proposes a solution approach to manage the heating plans of tenants served by a district heating plant located in Sweden. To do that, the daily temperature request of each household in the associated pilot region is obtained, and the daily temperature profile of each household is optimized with the help of the proposed decision support system and smart valves. The hot water inflow rates of radiators are remotely controlled via smart valves at each flat to minimize the total energy consumption, carbon emission and cost associated with the energy consumption of the district heating plant. We aim to shave the peak demands while fully satisfying the temperature requests of households without violating their thermal comfort. Peak demand shaving is achieved by generating preheating schedules via mathematical optimization and using the thermal storage potential of the insulated flats. The resulting mathematical optimization model presents significant computational challenges that cannot be efficiently solved using optimization solvers within a reasonable time limit. To this end, we develop three genetic algorithm approaches that are computationally scalable for realistically-sized instances and verified to yield near-optimal solutions for the test instances. Extensive numerical analyses show the effectiveness of the proposed approach and the genetic algorithm since we yield significant carbon emission reduction and cost savings compared with the method that the experts of the utility company propose.

Resiliency Evaluation of Sheltering in a Net-zero Energy House During Summer Power Outage

This study examines the growing issue of power outages caused by natural disasters and proposes the use of net-zero energy houses (ZEH) as a safe alternative to traditional shelters. A ZEH, equipped with an independent energy system, can maintain essential living standards such as thermal comfort and 24-hour air conditioning during a summer power outage, reducing the risk of heatstroke. The research tested a ZEH in Japan, confirming its ability to support critical household appliances like refrigerators, lighting, and water heaters for up to 72 hours. This demonstrates the ZEH's potential for offering safe, comfortable shelter during emergencies while addressing problems like poor sanitation and lack of privacy found in typical shelters. The experimental ZEH is located in Shizuoka, Japan, is a steel structure, and has a floor area of 110.94 m2 and overall heat transmission coefficient (UA) of 0.48 W/m2ཥK. The ZEH was equipped with a 5.1 kW photovoltaic system and 5.6/11.2 kWh storage battery (BT), which produced an output of up to 2.0/4.0 kVA. A ZEH with a 5.6 kWh BT can provide for ventilation and living/dining room/kitchen air conditioning (AC), refrigerator, television, lighting, mobile phone charging, rice cooker, microwave, electric kettle, and heat pump water heater during a 72-h power outage. The ZEH with a 11.2 kWh BT can also provide bedroom AC and high-load home appliances for lunch and dinner, in addition to a 5.6 kWh BT. The use of AC in a self-supporting circuit maintained the thermal environment at a low heat stroke risk.

A WRF-UCM-SOLWEIG framework for mapping thermal comfort and quantifying urban climate drivers: Advancing spatial and temporal resolutions at city scale

The capability to evaluate city-scale outdoor thermal comfort is crucial for understanding the public's experience of heat stress, especially during heat waves. Nevertheless, there remains a methodological gap in accurately mapping thermal comfort with high spatial and temporal resolutions in complex urban environment and in quantifying the contributions of various urban climate drivers, such as sky view factors and tree canopy fraction. To bridge this gap, we propose an innovative WRF-UCM-SOLWEIG framework that couples a mesoscale model with an urban microclimate model. Specifically, it integrates the Weather Research and Forecasting model coupled with the urban canopy model (WRF-UCM) and the Solar and Longwave Environmental Irradiance Geometry model (SOLWEIG). This framework is then applied to a densely populated tropical city in China, to quantify the impact of urban climate drivers on the Universal Thermal Climate Index (UTCI). The results reveal a significant diurnal variation in the impact of urban morphology. Notably, the most significant drivers affecting daytime UTCI are the impervious surface fraction and the tree canopy fraction, with maximum Pearson's correlation coefficients of 0.80 and -0.70, respectively. These findings suggest that urban heat mitigation strategies should prioritize on reducing impervious surfaces and enhancing shade management, alongside expanding urban forestry measures.

Multi-objective optimization of building energy consumption and thermal comfort based on SVR-NSGA-II

It is necessary to reduce the huge energy consumption of buildings while ensuring indoor thermal comfort. The building envelope design notably affects the energy consumption and indoor thermal comfort. This study proposes a framework of support vector regression non-dominated sorting genetic algorithm-II (SVR-NSGA-II) to study the multi-objective optimization of buildings and discover the best building envelope design. First, the data are obtained by OpenStudio 1.1.0 simulation. Then SVR is used to describe the relationships between the parameters and the two objectives. Using SVR models as the objective functions, NSGA-II is applied to optimize the objectives. Finally, taking a proposed office building as an example, the developed framework is applied, verifying its feasibility and effectiveness. The optimized parameters of the building envelope are as follows: the exterior wall U-value, roof U-value, exterior wall U-value, solar heat gain coefficient value (SHGC), and south, north, east, west window-to-wall ratios are respectively equal to 0.664 , 0.393 , 1 , 0.381, 0.697, 0.7, 0.273, and 0.254. The design of the proposed building can be modified to provide a more energy efficient and comfortable building. The proposed model saves time and simplifies operation compared with traditional building information modeling methods.

Predictive building energy management with user feedback in the loop

Retrofitting buildings with predictive control strategies can reduce their energy demand and improve thermal comfort by considering their thermal inertia and future weather conditions. A key challenge is minimizing additional infrastructure, such as sensors and actuators, while ensuring user comfort at all times. This study focuses on retrofitting with intelligent software, incorporating the users’ feedback directly into the control loop. We propose a predictive control strategy using an optimisation-based energy management system (EMS) to control thermal zones in an office building. It uses a physically motivated grey-box model to predict and adjust thermal demand, with individual zones modelled using an RC-approach and parameter estimation handled by an unscented Kalman filter (UKF). This reduces deployment effort as the parameters are learned from historical data. The objective function ensures user comfort, penalises undesirable behaviour and minimises heating and cooling costs. An internal comfort model, automatically calibrated with user feedback by another UKF, further improves system performance. The practical case study is an office building at the ”Innovation District Inffeld”. Operation of the system for one year yielded significant results compared to conventional control. Thermal comfort was improved by 12% and thermal energy consumption for heating and cooling was reduced by about 35%.

Controlled airflow fluctuations for improved performance of mist cooling systems: Enhanced evaporation and thermal comfort

Rising global temperatures and resulting heat stress on people necessitate sustainable outdoor cooling solutions. Mist cooling offers promise, and this work proposes a novel approach: incorporating fluctuating airflows into misting systems. We hypothesize that mist-cooled fluctuating airflows could provide more efficient outdoor cooling for people, for two reasons: 1) Increased turbulence and mixing promoting higher water evaporation rates; 2) dynamic airflow leveraging transient thermal perception for improved comfort.Wind tunnel experiments and numerical simulations support this hypothesis, revealing that fluctuating flow, compared to constant flow with the same average velocity, enhances evaporation. Lower frequencies, higher amplitudes, and profiles with steeper gradients led to higher evaporation rates. These findings assume an idealized domain, excluding natural wind patterns. Furthermore, predictions confirmed that fluctuating flows consistently provide superior thermal comfort compared to constant flows. Fluctuating airflow with misting achieved equivalent comfort at 38% lower energy consumption compared to fluctuating flow without misting and 81% lower compared to constant flow with misting. The proposed technology has the potential to improve outdoor comfort and decrease resource consumption. It is scalable, not complex, and can be implemented into existing systems, though it may face challenges such as increased wear on fan components.

A hierarchical framework for aggregating grid-interactive buildings with thermal and battery energy storage

The behind-the-meter (BTM) thermal and battery energy storage can help improve energy efficiency, reduce energy costs, and enhance energy resilience, particularly in rural areas and for disadvantaged communities. Aggregating numerous BTM energy storage systems can act as a price influencer with a significant source of load shifting and peak demand reduction. An integrated and scalable control mechanism is required to effectively utilize energy storage systems and flexible building loads to maximize the economic benefits, considering various distribution system constraints. This paper presents an innovative hierarchical coordination framework for energy storage and flexible load in buildings, considering various factors such as electricity prices, thermal comfort, and distribution system modeling and constraints. At the upper level, a distribution system operator optimizes the power flow to minimize its power procurement costs from the electricity wholesale market, while at the lower level, aggregators determine the optimal dispatch of battery and thermal energy storage systems in multiple buildings on behalf of end-users to minimize operating costs according to the power prices. These problems are solved using a game-theoretic approach through negotiations between the distribution system operator and aggregators as a bi-level decision model. Simulation case studies have been performed for a test distribution network with a number of building end-users using energy storage systems to quantify the performance of aggregators. The results demonstrate that the proposed strategy can reduce peak load for a reliable electricity distribution network while saving electricity bills for customers.

Assessing functional, comfort and aesthetic needs of Indian male riders from motorcycle clothing

The number of motorcycle riders is growing at a phenomenal rate in India and so is the number of crashes involving them. The use of motorcycle protective clothing (PPE) is known to reduce the severity of soft tissue injuries to motorcyclists in the case of a crash. The PPE currently available in India is imported and not designed to meet the unique weather, road, and riding conditions prevalent in India. In this study, a conceptual framework based on Functional, Comfort and Aesthetic (FCA) requirements of motorcycle riders is proposed for the design of motorcycle PPE. Data regarding the FCA requirements of Indian riders was collected through a questionnaire. Riding habits, risk factors, factors affecting the buying decisions for motorcycle clothing, awareness regarding protection standards, satisfaction with currently owned motorcycling clothing and requirements of comfort and aesthetics from motorcycle clothing were studied. 217 Riders aged 18–45 years from 10 major Indian cities responded to the online survey questionnaire. Most riders reported facing heat stress, wet stress (dues to sweating), restricted mobility, and dissatisfaction with the fit of the currently available motorcycle clothing. Satisfaction with the available colours and styles was also reported to be low. The results of the survey show that currently available riders’ clothing is not as per requirements of Indian riders. It fails to provide adequate thermal comfort to users, which may compromise rider safety during long rides. Findings of this study can be used by motorcycle clothing designers and manufacturers to design clothing as per the requirements of Indian riders. Improved thermal and psychological comfort can improve rider focus, may contribute to crash prevention and protect the rider from grievous injuries during a crash.

Investigation on Thermal Performance in Japan’s Local Station and Shopping District during Cold Season: Study Case of Kurosaki Arcade

Abstract This research delves into the spatial and thermal comfort conditions within the Kurosaki Shopping District, a market with a century-long history in Kitakyushu, Fukuoka. Despite the existing uncomfortable thermal conditions during winter, users actively engage in outdoor activities such as selling and opening stores. This research aims to understand the condition that the local user had to frequently withstand in the semi outdoor and outdoor area of Kurosaki District station and market’s urban area. Identifying issues related to thermal comfort in the outdoor areas, the study focuses on measuring and analyzing crucial parameters including air velocity, humidity, temperature, and spatial conditions. The method of data gathering uses Anemometer, Thermal recorder, and Globe Thermometer are utilized in 5 selected public areas that is actively frequented by local users. The research employs a comparative analysis method, juxtaposing the collected data with findings from literature reviews on standards and general comfort temperatures. The analysis reveals that temperature fluctuations are influenced by geographical factors and activity levels. The lack of building density contributes significantly to deviations in temperature and humidity from established standards. The study highlights the importance of addressing climatic conditions to enhance comfort in open spaces, especially in historically significant markets with extended operational histories. This research is expected to help policy makers understand the conditions of the local users and gather data for further research in the future.

Performance analysis and thermal comfort evaluation of a CO2 transcritical air-conditioning system for cabin thermal management of electric vehicles

This study investigates the effects of different operating conditions on system performance and optimal discharge pressure by establishing a numerical model of CO2 cabin thermal management system and validating the model with experimental data. Besides, two different optimal discharge pressure formulas are attained based on different parameters. It is found that the multi-parameter formula is more accurate than the other with a maximum deviation of 2.64%. Then, the control strategy is designed based on this formula to investigate the coupled effects of thermal comfort and economical performance under different driving patterns and different ambient temperatures. The elevation of PMV indicator can weaken the declining rate of power and energy consumption, enhance the driving range and reduce annual operation cost in cooling mode (AOCc) of vehicle. The boundary of thermal comfort zone (PMV = 0.5) exhibits excellent economical efficiency due to its higher growth rate of driving range (6.3%) and reduction rate of AOCc (7.9%) from 0 to 0.5 PMV at the ambient temperature of 35 °C. And this improvement is more prominent under higher ambient temperature.