Thermal Performance Indicators Research Articles

Performance analyses on the air cooling battery thermal management based on artificial neural networks

Air cooling thermal management technology is a lightweight and cost-effective approach for managing heat in power battery packs for electric ships. However, it suffers from significant drawbacks such as poor temperature control and excessive noise generation. To address these challenges, this study proposes a method that combines fluid dynamics and artificial neural networks (ANNs) to optimize the thermal management and aeroacoustic performance of the air cooling battery thermal management system (BTMS) for marine power batteries. Initially, a thermal-flow coupled model and an acoustic model for the BTMS were developed to investigate the impact of system structural parameters (battery spacing d, and main channel inclination angle θ) and operating parameter (system inlet velocity v) on the thermal management performance indicators (maximum temperature Tmax, and maximum temperature difference ΔTmax) as well as the aeroacoustic performance indicator (overall sound pressure level, OSPL). Subsequently, a relationship between the system structural and operating parameters and performance indicators was established using the 50-layer Residual Network (ResNet-50) model, enabling accurate and rapid prediction of the system thermal management and aeroacoustic performance. Furthermore, by combining ResNet-50 with the evaluation method of Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), this study successfully obtained the optimal system structure and operating parameters. The research indicates that keeping the remaining parameters constant, increasing the battery spacing results in higher maximum temperature and maximum temperature difference, while decreasing the overall system sound pressure level. Conversely, increasing the main channel inclination angle results in lower maximum temperature and maximum temperature difference, but higher overall system sound pressure level. In addition, increasing the inlet velocity will result in higher maximum temperature and maximum temperature difference, as well as higher overall system sound pressure level. The optimal case were found to be a main channel inclination angle θ = 3°, battery spacing d = 2 mm, and inlet velocity v = 10 m⋅s−1. Compared to the base case, the optimal case shows a maximum temperature reduction of 10.63 K, a maximum temperature difference reduction of 9.41 K, and an overall sound pressure level reduction of 4.6 dB. The prediction errors for these values are 0.08 %, 2.64 %, and 1.36 % respectively. This research demonstrates an effective and rapid approach based on fluid dynamics and ANNs in the design and optimization of BTMS.

Performance monitoring of heat exchanger networks using excess thermal and hydraulic loads

Fouling in heat exchanger networks (HENs) affects thermal and hydraulic efficiencies resulting in economic penalties to the process industries. Conventionally, overall heat transfer rates of the heat exchangers in HENs are monitored to identify fouling. However, apart from fouling, these rates also vary with inlet conditions. Hence, estimating the degree of fouling accurately based only on heat transfer rates can fail. Previously, we had proposed the use of excess thermal and hydraulic loads as the basis for monitoring fouling in standalone exchangers (Patil et al., 2022). These are quantified as thermal and hydraulic performance indicators that can be easily tracked through suitably constructed charts. In this paper, we extend the approach to HENs wherein deviations in temperature drop across a heat exchanger vis-à-vis the clean condition also depends upon upstream heat exchanger(s). The network performance monitoring charts rely on normalized performance indicators and temperatures across heat exchangers and also have explicitly denoted normal, alert, and alarm regions. The proposed charts are applicable to HENs with or without temperature controllers. Two case studies comprising multiple scenarios of flow rate and setpoint changes are studied. The results show that the method can effectively identify the degree of fouling.

Use of modern algorithms for multi-parameter optimization and intelligent modelling of sustainable battery performance

The focus of this computational work is to predict and optimize the battery thermal performance indicators for its sustainable operation using different meta-heuristic optimization algorithms and machine learning models. The contribution of this work is two-fold, first, the heat removal ability from battery indicated by average Nusselt number (Nuavg) and hotspots (MaxT) to avoid battery thermal runaway are optimized as single objective optimization (SOO) and as multi-level objective optimization (MOO) problem. Second, intelligent algorithms: Gradient boosting (GB) algorithm and Gaussian process regressor (GPR) algorithm are used for modelling of Nuavg and MaxT. For SOO, Multi-verse optimization (MVO) and Grey wolf optimization (GWO) algorithms are used for individual battery performance indicators. Similarly, the enhanced version of MVO and GWO for MOO (MMVO and MGWO) algorithms is customized. Each algorithm is operated for five cycles and 100 iterations in each cycle of execution. In GB algorithm the effect of different loss functions and in GPR algorithm the effect of parameter alpha (α) is analyzed. SOO gives highest fitness of Nuavg and lowest hotspots occurrence from both the algorithms with same converged positions of operating parameters. MMVO and MGWO relatively provide lower Nuavg with MaxT in the same range of SOO. The MOO provides different set of particle positions compared to SOO. MGWO algorithm has outperformed in providing the best non-dominated solution. The GB and GPR algorithm are good enough for the forecasting of battery thermal parameters. GPR is even accurate, however the range of α is important during training and testing. The best Nuavg obtained from SOO using MVO algorithm is around 82.06 while MaxT is 0.34. The same from GWO algorithm is 82.05 and 0.33 respectively. MGWO algorithm in MOO provides Nuavg and MaxT around 75.57 and 0.34 while MMWO provides 66.76 and 0.33 respectively. GPR algorithm gives accuracy as close as 98 % for MaxT while it gives 94 % accuracy for Nuavg. On the other hand GB algorithm gives 99 % and 97.5 % accuracy for MaxT and Nuavg respectively.

Heat transfer enhancement in cold plates with wavy channels via free-shape modeling and optimization

The objective of this study is to improve heat transfer performance of cold plates with wavy channels typically used in Battery Thermal Management Systems (BTMSs). The means of enhanced design flexibility based on parametric modeling allows for the free construction of wavy geometry in terms of amplitudes, wavelengths, waveforms, and cross-sections. The fixed dimensions are “liberated” into these four degrees of freedom, which helps to find the optimized wavy structures with the superior cooling performance. Based on the proposed free-shape modeling framework, the Horizontal Wavy Channel (HWC) and Radial Wavy Channel (RWC) are constructed, and these single channels can be considered as the basic structure of cold plates. One of the most popular evolutionary algorithms, NSGA−II, is utilized to optimize these two types of channels. The average temperature (overall thermal performance) and root mean square temperature (temperature uniformity) of top and bottom surfaces of cold plates are specified as the objective functions. In addition, to better verify the validity of the proposed method, empirical-based uniform HWC (UHWC) and RWC (URWC) are given as further comparisons. Based on the obtained Pareto front and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method, when the weight coefficients of the two thermal performance indicators are set to 0.5:0.5, the best compromised solutions are obtained: VHWC−22 for HWC and VRWC−30 for RWC. The results further show that the ranking of excellent overall thermal performance is VHWC−22 > URWC >≈ VRWC−30 > UHWC, while the ranking of excellent temperature uniformity is VRWC−30 > VHWC−22 > URWC > UHWC. Obviously, the variable wavy channels are generally superior the uniform wavy channels in terms of thermal performance. This work provides a guideline for the design of wave structures that can be used not only in cold plates but also in heat sink with fins, heat exchangers, and other components with wave structures.

Experimental and numerical investigation of sulfuric acid decomposition for hydrogen production via iodine–sulfur cycle

In the context of global warming and the greenhouse effect, the iodine–sulfur cycle is an important method of producing hydrogen on a large scale with low carbon emissions using nuclear energy for future applications. The sulfuric acid decomposition reaction is a key step in this process. A sulfuric acid decomposer with good performance usually has the characteristics of high decomposition rate, small pressure drop loss and reasonable temperature distribution, which can ensure the efficient and stable process of sulfuric acid decomposition. Therefore, an accurate evaluation of the performance of the sulfuric acid decomposer unit and the reproducibility of the whole process is of utmost importance for designing and engineering an actual system for hydrogen generation. In this work, two sets of experimental systems were designed to measure the important kinetic parameters of sulfuric acid decomposition reaction and to determine the thermal hydraulics and chemical reaction performance indicators of the system. Then, a multi-field coupling model in which the phase change and chemical reactions were coupled by user-defined functions was developed based on the experimental kinetic parameters to account for the whole process. The thermal–hydraulic characteristics and the chemical reaction indexes predicted by the model are in good agreement with the experimental results. The maximum errors of the sulfuric acid decomposition fraction and pressure drop do not exceed 5% and 10%, respectively. Overall, this work provided a complete model for predicting the performance of the sulfuric acid decomposer.

Collective behavior of boreholes and its optimization to maximize BTES performance

Borehole layout strongly affects the behavior of borehole heat exchangers (BHEs) and changes the performance of a borehole thermal energy storage (BTES). This study investigates the existence and importance of the optimum collective behavior of BHEs to maximize the performance of BTES. Charge benefit ratio, storage efficiency and configurational benefit factor are proposed as performance indicators for better and finer performance evaluations of BTES systems. A small-scale BTES consisting of ten boreholes arranged on a concentric double-ring layout is considered as an application. Performance variations with the inner and the outer radii of the borehole field are analyzed for the first five years of operation. The temperature fields of different configurations show the transition from collective to individual behavior of boreholes, which leads to an optimal radial configuration maximizing the performance indicators. It is seen that the indicators strongly depend on both inner and outer radii and they reach their maximums for the same distinct radial configuration. The optimum arrangement can almost double the thermal performance indicators. It is thus of great importance to optimize collective behavior to maximize the usage of stored thermal energy. The results are qualitatively general and represent the common behavioral patterns of BTES systems.

Upgrading the performance of a solar air collector with flexible aluminum air ducts and graphene nanoplatelet-enhanced absorber coating

Solar air collectors (SAC) have had great importance nowadays as far as clean energy production is concerned. In this study, the novel double flow solar air collectors were designed and their performance was investigated. This study aims to illustrate how affect the thermal performance and sustainability indicators of a newly-designed solar air heater with nano-enhanced aluminum air ducts instead of conventional sheet metal absorber plate. Two double flow solar air collectors, the former of which includes flexible aluminum air ducts coated by black matte paint (DSAC/FAD), whereas the latter one includes sheet metal plate coated by black matte paint (DSAC) were studied under the same environmental conditions. Moreover, the effect of nanoparticles on performance was investigated by adding nanoparticles into the paint. For this purpose, a set of experiments were simultaneously performed utilizing solar air collector with flexible aluminum air ducts coated with black matte paint (DSAC/FAD) and the double flow solar air collector with flexible aluminum air ducts coated with graphene nanoplatelet-included black matte paint (DSAC/NFAD). The experiments were conducted with the same fans of 40 W power. The energy, exergy and such sustainability indicators as waste exergy ratio (WER) and sustainability index (SI) were examined for each design. In the second part of experiments, the maximum thermal efficiency was obtained as 73.94% for the (DSAC/NFAD). The COP values for DSAC (Day 1), DSAC/FAD (Day 1), DSAC/FAD (Day 2), and DSAC/NFAD (Day 2) were found as 4.82, 4.52, 4.56, and 5.22, respectively. Similarly, the mean exergy efficiency of the (DSAC/NFAD) was calculated as 37.73%, whilst DSAC had the mean exergy rate of 17.93%. For the sustainability indicators, the best results of WER and SI were achieved in the experiments conducted on DSAC/NFAD. It was concluded that the double flow solar air collector with flexible aluminum air ducts can be utilized for thermal performance enhancement. Moreover, it is predicted that the outcomes of this study enlightened the new research topics to be emerged.

Numerical Investigation on the Thermal Protection Characteristics of a New Active Jet Design Parameter for Hypersonic Flight Vehicle

This study investigated the thermal protection performance of an active jet thermal protection system (PRsAJ-TPS) based on a new jet design parameter PRs for hypersonic flight vehicles (HFVs). The new parameter PRs is defined as the relationship between the jet flow total pressure and the free flow total pressure behind the outer bow shock. A 20° tilted nozzle design is employed together with the PRs to form the PRsAJ-TPS. Theoretical and numerical analysis is performed to prove the advantages of using the PRs. A conventional in-house CFD solver with the k ‐ ω SST turbulence model is utilized to perform the calculation. The influence of different PRs (working in the short penetration mode) and flight angles of attack on the performance of the PRsAJ-TPS is also studied. The simulation results confirmed that with a constant PRs, the Mach disk location stays the same and the normalized heat flux reduction is similar at different flight conditions. Nearly linear relationships exist between the new design parameter PRs and thermal protection performance indicators. The PRsAJ-TPS also exhibits good protection when flight angle of attack (AoA) varies between 0° and 40°, with the best results achieved at AoA = 0 ° . This study provides valuable information for the engineering application of the jet-based TPS to future HFVs.

Thermal energy storage enhancement of a forced circulation solar water heater’s vertical tank unit using phase change material

This work aims to investigate the thermodynamic effect of phase change material integration within vertical storage tanks that are connected to forced circulation solar water heaters, on their thermal energy storage capability. The phase change material is encapsulated in cylindrical and elliptical capsules, which are integrated at the bottom, middle and top sections of the tank. Hence, three parametric studies were carried out depending on the geometry of the encapsulation, besides to their integration position inside the tank, through computational fluid dynamic calculations. The numerical model was established under “OpenFOAM” and the enthalpy-porosity method for the phase change phenomena modeling was validated against the experimental data of the literature. For this purpose, the following thermal performance indicators were used: temperature, liquid fraction contours and the tank’s energy storage efficiency. It was found that the time required for a complete melting of the phase change material inside the cylindrical capsules is higher than that of the elliptical ones (beyond 17.50 s), for a fixed integrating location. Otherwise, 21, 23 and 17.50 s were necessary for the melting of the phase change material filling the vertical ellipse (top configuration), horizontal ellipse (bottom configuration) and cylindrical cavity (middle configuration) respectively. In addition, results showed that the shapes of phase change materials affect the thermal storage efficiency. For example, 25, 28 and more than 40 s were sufficient to reach 100% of the vertical tank’s storage efficiency for the following top configurations: vertical ellipse, horizontal ellipse and cylindrical cavity, respectively. Finally yet importantly, integrating the phase change materials at the middle section of the tank can be considered as the optimal configuration, because it allows a gain of 2 °C compared to the bottom and top zones.

Performances and control aspects of steam storage systems with PCM: Key learnings from a pilot-scale prototype

Medium and High temperature steam is used as Heat Transfer Fluid in a wide range of industrial processes. Steam storage is required when steam production or consumption is variable in time, like in solar thermal facilities or batch industrial processes. In introduction, this paper gives an extensive review of the PCM storage prototypes that were operated worldwide for steam applications between 120 and 400 °C. At CEA Grenoble, a PCM steam storage prototype was operated during >300 days during three tests campaigns from 2013 to 2019. 78 charge–discharge cycles were performed with the same PCM volume under a wide range of operating conditions. This paper aims at reporting some significant experimental results obtained from this prototype. Thermal performance indicators (storage capacity, utilization rate, storage efficiency, and exergy efficiency) are evaluated in detail for the first time for a pilot scale PCM steam storage. For a complete charging-discharging cycle at sliding pressure, constant mass flow, and from homogeneous temperatures in initial conditions, utilization rate is estimated at 81.9%, storage efficiency at 79.3%, and storage exergy efficiency at 76.2%. From 2013 to 2019, thermal testing of the storage prototype showed very repeatable results: in this paper, the authors demonstrate that heat transfers were not altered between 2013 and 2019. Beyond most commonly used operating modes for PCM steam storage (fixed pressure and sliding pressure), advanced control strategies are proposed. Two examples of advanced controls are described in this paper, showing an insight of the valuable services that a PCM storage system can provide to an industrial steam user (power cycle, industrial steam network,…).

Fluid flow and heat transfer of porous TPMS architected heat sinks in free convection environment

Heat dissipation in electronic devices is challenging due its limited size and cooling space constraint. Implementing Triply Periodic Minimal Surfaces (TPMS)-based cellular structures could enhance the thermal exchange mechanism due to their novel architected, interconnected, and inter wind porous topologies and high surface area to volume ratio. In this study, three novel mathematically-driven TPMS heatsink structures were investigated using computational fluid dynamics (CFD) based models. TPMS heat sinks consisting of seven triply periodic unit cells were examined to investigate their thermal performance and fluid flow behavior in free convection air environment. The thermal performance indicators as convection heat transfer coefficient and surface temperature under parametric variation of applied heat load, fluid enclosure boundary condition, and TPMS structure orientation were determined. Enclosure boundary conditions found to have a significant effect on the thermal behavior of each heat sink structure; including radiation contribution was found to account for approximately 23% of the overall heat transfer in due to the complex TPMS internal structure. Three empirical Nusslet number correlations were then derived for the investigated TPMS structures. The results showed that TPMS-based heat sinks outperform conventional heat sinks by 48–61% owing to the random perturbations of flow and high packing density. This work shows the potential of TPMS porous architectures as very promising heat sinks.

Balancing daylight in office spaces with respect to the indoor thermal environment through optimization of light shelves design parameters in the tropics

The study aims to investigate the preferred daylighting availability ranges for the best visual and thermal comfort in office workspace through optimal modifications light-shelve parameters, grounded on parametric design and optimization, with a focus on its visual and thermal indices. To identify the final optimal solutions, single and multi-optimization scenarios were used. The findings revealed that optimizing for a single objective might obstruct the attainment of other goals. In other words, the first scenario, optimization only for daylight availability, results in an increase in temperature. While optimizing for indoor thermal performance solely, none of the preset daylight availability acceptance requirements were met. However, multi-objective optimization solutions were the final optimal solutions nearest to the ideal. Final optimum solutions of the best design parameters of light shelves can improve the total average of daylight availability by 56.25%, 50.63%, 57.50% and 71.88%, and the indoor thermal performance was improved by decreasing the average temperature for thermal environmental performance indicators by 4.15%, 3.27%, 3.17% and 4.76%, respectively, in March, June, September and December. The study concludes that daylighting levels of 500 lux to1300 lux provide the best range of optimal daylighting for visual and thermal comfort indicators for office spaces in the tropics.

Monitoring fouling in heat exchangers under temperature control based on excess thermal and hydraulic loads

Fouling affects heat exchangers’ performance leading to additional utility requirements and economic penalties. Performance monitoring is required to ensure that exchangers operate within allowable limits. Conventional techniques use overall heat transfer rate to monitor thermal performance. These techniques fail when the heat transfer rate remains constant, which is the case anytime a heat exchanger has feedback control on temperature. In this paper, we propose an approach to monitor fouling in heat exchangers that have closed-loop control. Our approach is based on excess pressure drop and thermal load. A monitoring chart is also proposed based on combined hydraulic and thermal performance indicators. The proposed monitoring charts are demonstrated on two case studies – a cooler with a utility on the tube-side and a heater with the utility on the shell-side. The results show that even when setpoints and flowrates change due to process requirements, the proposed approach can effectively monitor fouling and identify if the operation is within allowable performance bounds. The results can be used to schedule the cleaning of the exchangers at an appropriate time so as to avoid excessive economic losses.

Assessment of Different Envelope Configurations via Optimization Analysis and Thermal Performance Indicators: A Case Study in a Tropical Climate

Passive solutions for more energy-efficient buildings are critical to improving our odds in the current energy crisis. This work focuses on assessing the thermal performance of different envelope construction layouts in a tropical climate through proposed indicators regarding the thermal mass degree (TMD) and insulation degree (ID). For this, a numerical study was performed for a reference building (RB) in Panama City and validated with the electricity consumption bills. Behavioral and sensitivity analyses were employed to identify critical heat gains and the most important envelope constructions, resulting in the layouts of the roof and external walls. Optimization analyses were performed to find adequate layouts to reduce the discomfort hours. Different roofs, external walls, internal partition layouts, and glazing types were evaluated. Results indicated that the adequate envelope configuration is a roof layout with low TMD and ID, along with wall layouts with high TMD and low ID.

In-Situ Thermal Bridge Evaluation of a Building Using Bayesian Inference With Measured Infrared Thermography

Abstract Useful thermal bridge performance indicators (ITBs) of existing buildings may differ from calculated thermal bridge performance derived theoretically due to actual construction conditions, such as irregular shapes and aging. To fill this gap practically, a more realistic quantitative evaluation of thermal bridge on-site needs to be considered to identify thermal behaviors throughout exterior walls and thus improve the overall insulation performance of buildings. In this study, a case study is conducted using an infrared thermal imaging method to evaluate the thermal bridge of an existing building practically. The study's main purpose is to review the thermal bridge performance indicators measured by the steady-state model under field conditions in terms of convergence and uncertainty. Bayesian Markov Chain Monte Carlo (MCMC) is used to examine the validity of the results by deriving evaluation results in the form of distribution, including uncertainty. After the measurement was completed, an analysis of the results was conducted. As a result of measurement for 3 days, it was found that the thermal bridge part had 1.221 times more heat loss than the non-thermal bridge part, which showed a 6.7% deviation from the numerical method. However, the uncertainty was 0.225 (18.4%, CI 95%), a large figure. This is due to the influence of field conditions and shows the limitations of the steady-state measurement model. Regarding the convergence of the results, the measurement results were found to converge continuously as the measurement time increased. This suggests that valid results can be obtained in the field if the measurement is performed for a sufficient time, even with a thermal bridge measurement method assuming a steady-state.

Long term performance monitoring and KPIs’ evaluation of Aquifer Thermal Energy Storage system in Esker formation: Case study in Stockholm

The majority of Aquifer Thermal Energy Storage (ATES) systems studies have been conducted in aquifer systems located in large sand aquifers. Esker formation present a more challenging geometrical complexity compared to typical sand aquifers. This study aims to conduct comprehensive and long term performance evaluation of doublet type ATES system in esker geological formation in Stockholm, Sweden. The total heating and cooling used from the ATES are 673 MWh and 743 MWh respectively during the first 3 annual storage cycles of operation. The licensed total amount of water extraction and injection is 50 liters per second with undisturbed groundwater temperature of 9.5°C. Over the first three storage cycles, the average injection and extraction temperatures for the warm side are 13.3°C and 12.1°C, and for the cold side 7.6°C and 10.5°C. The average temperature differences across the main heat exchanger from the ATES side are 4.5 K during winter and 2.8 K during summer which is 4-5 degrees lower than the optimum value. The average thermal recovery efficiency over the first 3 storage cycles were 47 % and 60 % for warm and cold storages respectively. The data analysis indicated annual energy and hydraulic imbalances which results into undesirable thermal breakthrough between the warm and cold side of the aquifer. This was mainly due to suboptimal operation of the building energy system which led to insufficient heat recovery from the warm side, and subsequently insufficient cold injection in the cold wells, despite the building heating demand and the available suitable temperatures in the ATES. The cause of the suboptimal operation is the oversizing of the heat pumps which were designed to be coupled to larger thermal loads as compared to the ones in the final system implementation. As a result, the heat pumps could not be operated during small-medium loads. Additionally, the paper discusses the limitations of currently used energy and thermal key performance indicators (KPI) for ATES and propose an additional thermal KPI named heat exchanger efficiency balance (βHEX) that connects and evaluate the optimum operational point of temperature differences from both the building and ATES prospective. In addition to ATES energy and hydraulic KPIs, βHEX can contribute in providing more complete picture on the ATES-building interaction performance as well as highlights if the losses in energy recovery from ATES are due to the subsurface processes or building energy system operation which has been proven to be critical for the optimum ATES performance.

Thermal performance of residential building with mixed-mode and passive cooling strategies: The Brazilian context

The definition of user behavior in computer simulations for building thermal performance analysis is a challenging and complex task. People behave differently depending on their routine and culture, among many other factors. Thus, in this study, mixed-mode climatization for cooling and heating (air conditioning and natural ventilation) was analyzed considering different thermal performance indicators, construction systems and climates in Brazil. The typology analyzed was a single-family dwelling. The results showed not only how different cooling strategies can change the dwelling thermal performance, but also how this performance may be perceived differently based on the indicator. Depending on the indicator, distinct envelopes would be recommended. Also, the study demonstrated that for public policies, the stakeholders need to understand the behavior and occupancy patterns of residents who are representative of a country in order to identify, with more accuracy, the most appropriate envelope for each case. In the case of the indicators, metrics that are most easily adapted to considerer resilient according to climate changing are recommended for inclusion in standards and regulations.

3D virtual technology for space design in green building energy-saving design

In order to solve the problem that the traditional green building energy-saving design method does not establish a 3D model, resulting in poor energy-saving effect and low accuracy of information collection, this paper proposes a 3D virtual technology of space design in green building energy-saving design. The sketch modelling method is used to build the three-dimensional virtual model of green building, and the initial model is drawn by using UVW map coordinates in 3dsmax software. The maintenance information, meteorological parameters, indoor and outdoor ventilation information of green energy-saving buildings are obtained by using GIS technology, and relevant information is imported into DeST-c software to simulate and analyse the thermal balance of green buildings. It is graded by stages, and different thermal performance indicators are obtained to simulate the energy consumption of green buildings. The experimental results show that this method can accurately collect building information in green building energy-saving design, and greatly reduce building energy consumption.

ОБОСНОВАНИЕ ХАРАКТЕРИСТИК МНОГОСЛОЙНОЙ СТЕНОВОЙ КОНСТРУКЦИИ С ИСПОЛЬЗОВАНИЕМ СРЕДСТВ КВАДРАТИЧНОГО ПРОГРАММИРОВАНИЯ

High requirements for the energy efficiency of residential construction projects being built, a high level of competition between building organizations, as well as a wide variety of applied materials and technologies determine the high importance for solving of the problems connected to determination of the characteristics of external multilayer wall structures. On the basis of the results received during the analysis of the relevant scientific developments, it has been concluded that the existing tools are limited in terms of taking into account thermal performance indicators as criteria for determination of the optimal values for the characteristics of the structure – particularly, the thickness and thermal conductivity of the structural layers. The expediency of conducting of the research aimed to the development of a tool for the determination of the characteristics for a multilayer wall structure on the basis of quadratic programming has been substantiated.

Development of a simplified thermal performance prediction method based on free-running temperatures and building envelope characteristics

Various thermal prediction methods and tools for conceptual building design have been rapidly developed in the past decades. However, most of these methods have some drawbacks to obsess their applications, such as heavily relying on very detailed information of building envelope components, and their thermal conductivity data with complicated computation models or formulas; and difficulties for architects to understand and judge the outcomes of such predictions in a conceptual design. Therefore, this research targets on developing a simplified method to predict the integrated thermal performance of a building with simplified envelope parameters and hourly free-running temperatures in the conceptual design stage. It categorizes the scattered design parameters into three combined thermal characteristic indexes and applies a serials of corresponding quasi-steady calculation methods for building thermal processes to predict hourly free-running temperatures. The interrelationships between these three combined indexes and two overall thermal performance indicators are verified via a sensitivity analysis, and are presented in two charts, which can easily be adopted in a conceptual building design. This method has been validated in an experimental case study. It can help architects to quickly find the thermal design performance of a designed building in the conceptual design stage.