Heat Balance Method Research Articles

Comparative assessment of simple and detailed energy performance models for urban energy modelling based on digital twin and statistical typology database for the renovation of existing building stock

The renovation wave calls for an integrated, participatory, and neighbourhood to neighbourhood approach tailored to the local environments. This can be hindered by the lack of geometric and performance input data about the existing building stock. A parametric digital urban building energy modelling (UBEM) tool was developed for local municipalities to automate calculations for comprehensive renovation strategies utilizing public databases specifically at the neighbourhood level. This article compares the accuracy of two energy performance calculation models (seasonal heat balance method and hourly resistance–capacitance method) used within the tool to detailed energy simulation software and measured energy consumption data of existing group of residential buildings in a same neighbourhood. The accuracy for estimating the total primary energy demand was roughly below 10 % for both simplified models. The seasonal calculation method showed consistent overestimation of space heating, depending on building characteristics. Solar and internal heat gains significantly affect the accuracy of simplified heat balance calculations, particularly in well-insulated buildings, while the more detailed 5R1C lumped capacitance hourly method provides improved accuracy for space heating demand. The comparison of uniform (proportional) and project based window area distribution used in the calculation models showed only marginal difference. The study validated simple seasonal and 5R1C hourly calculation methods using data from an apartment building neighbourhood with 22 apartment buildings. Despite larger deviations in the case of individual buildings, the average deviation from measured heating demand was only around 3 %, the seasonal method slightly overestimating and the 5R1C hourly method slightly underestimating the measured values. The primary energy demand including typical values of domestic hot water and household electricity was overestimated by both simplified methods due to lower electricity and water consumption in reality although the difference was below 7 % for the entire district. This concludes that pooling the building envelope heat loss calculation on a district level improves accuracy on average allowing better assessment of comparative renovation strategies.

Classification of radiant and convection time series for cooling load calculation of radiant cooling systems

Radiant cooling systems have the potential for energy saving, better thermal comfort, and space-saving. The lack of cooling load calculation methods limits the engineering application of radiant cooling systems. A universal radiant and convection time series (RCTS) set is indispensable in radiant cooling system design. In this study, an RCTS dataset with 100,000 sample rooms is generated based on the combinations of 9 room characteristic parameters. Extreme gradient boosting (XGBoost) is used to grade the room characteristic parameters and classify RCTSs. Gaussian mixture model (GMM) is used to extract the representative RCTSs for each category. The RMSE is used to measure the accuracy of the representative RCTS. The results indicate that XGBoost and GMM perform very well. Non-solar radiant time series (RTS), convection time series (CTS), solar RTS for radiant ceiling panel systems and solar RTS for radiant floor cooling systems are classified into 12, 8 and 1 categories, respectively. The representative RCTSs of all categories constitute a universal RCTS set. Fifteen room characteristic parameters are taken into account to construct sample rooms for Changsha. The accuracy of the representative RCTS was compared with the self-RCTS and heat balance method. The relative deviations of the design cooling load calculated using the representative RCTS and self-RCTSs were within ±3 % for 90 % cases of the sample rooms. The relative deviations between the design cooling load calculated using the representative RCTS, self-RCTSs, and theoretical design cooling load are within ±7 % for 90 % cases. The universal RCTSs set is applied for radiant cooling systems design.

Hourly estimation of water reaching the ground surface in snow-covered regions of Japan using mesoscale meteorological data with the heat balance method

In snow-covered regions, landslides, including debris flows, frequently result from snowmelt and cause significant hazards. Because these snowmelt-induced landslides are triggered by increasing groundwater level and pore-water pressure acting on the slip surface due to infiltration of snowmelt, sometimes mixed with rainwater, accurate estimation of water reaching the ground surface (abbreviated MR in this study) on an hourly basis is essential for developing countermeasures such as an early warning system. This study introduces a model for estimating hourly MR, as well as snow water equivalent and snow depth, using mesoscale meteorological data provided by the Japan Meteorological Agency. The model considers four processes: precipitation, snow accumulation and densification, snowmelt, and infiltration. In the snowmelt process, snowmelt is estimated using the heat balance method. We applied the model to a snow observation station in Niigata Prefecture, central Japan, where MR, snow water equivalent, and snow depth were observed during the winter seasons of 2017–18 through 2020–21. Comparisons of observed and calculated values demonstrated that the model successfully reproduced the observations, regardless of the amount of snowfall in individual winter seasons. We propose that this model can estimate hourly MR, snow water equivalent, and snow depth at any location in snow-covered regions where on-site meteorological and snow observations are unavailable.

Optimal classification of radiant time series for cooling load calculation of building air-conditioning systems

Building cooling load is caused by complex thermal effect. Design cooling load determines the capacity of air-conditioning assembly units and systems to maintain stable thermal environment and high operating efficiency. The radiant time series method (RTSM) is applicable for design cooling load calculation in engineering application. The radiant time series (RTS) should precisely match various room types by improving their accuracy and practicality. The room construction types require more explicit identification. This study proposes RTS classification method based on heat balance method (HBM) and CatBoost to obtain the representative RTSs for various room types. A new quantitative indicator, interior surface heat storage coefficient, is introduced to quantify the construction type. An accuracy evaluation is performed on the representative RTSs and design cooling loads calculated using them. The results show that interior wall type, ceiling type and floor type are important parameters for RTS classification. Compared to the HBM, the representative RTSs cause relative deviations of design cooling loads within 5 % for over 90 % of the room samples, with mean deviations within 2 %. This has demonstrated accurate RTS classification in this study. The appropriate representative RTSs with refined construction type can ensure accurate cooling load calculation and facilitate extensive application.

Heat Balance Method of Computing the Cooling Modes of Large-Sized Optics in Vacuum

Heat Balance Method of Computing the Cooling Modes of Large-Sized Optics in Vacuum

Disaggregation of canopy photosynthesis among tree species in a mixed broadleaf forest.

Carbon dioxide sequestration from the atmosphere is commonly assessed using the eddy covariance method. Its net flux signal can be decomposed into gross primary production and ecosystem respiration components, but these have seldom been tested against independent methods. In addition, eddy covariance lacks the ability to partition carbon sequestration among individual trees or species within mixed forests. Therefore, we compared gross primary production from eddy covariance versus an independent method based on sap flow and water-use efficiency, as measured by the tissue heat balance method and δ13C of phloem contents, respectively. The latter measurements were conducted on individual trees throughout a growing season in a mixed broadleaf forest dominated by three tree species, namely English oak, narrow-leaved ash and common hornbeam (Quercus robur L., Fraxinus angustifolia Vahl, and Carpinus betulus L., respectively). In this context, we applied an alternative ecophysiological method aimed at verifying the accuracy of a state-of-the-art eddy covariance system while also offering a solution to the partitioning problem. We observed strong agreement in the ecosystem gross primary production estimates (R2=0.56; P<0.0001), with correlation being especially high and nearly on the 1:1 line in the period before the end of July (R2=0.85; P<0.0001). After this period, the estimates of gross primary production began to diverge. Possible reasons for the divergence are discussed, focusing especially on phenology and the limitation of the isotopic data. English oak showed the highest per-tree daily photosynthetic rates among tree species, but the smaller, more abundant common hornbeam contributed most to the stand-level summation, especially early in the spring. These findings provide a rigorous test of the methods and the species-level photosynthesis offers avenues for enhancing forest management aimed at carbon sequestration.

Experimental study of heat transfer performance of industrial air cooler applying R449A instead of R507A refrigerant

Abstract In response to the problem of refrigerant pollution of the environment, this paper carries out research experiments on the performance of industrial air coolers using R449A and R507A refrigerants, comparing how refrigerant properties impact evaporator heat transfer performance. The parameters, such as the cooling capacity of the evaporator, were analyzed using the heat balance method. The results demonstrate that using R449A refrigerant in the evaporator at 0 °C enhances cooling capacity by 4.52% and heat transfer coefficient by 9.1% compared to the original R507A system. Using R449A refrigerant in the evaporator decreased the cooling capacity and heat transfer coefficient by 25% and 28.26%, respectively, at -18 °C, compared to the original R507A system. Studies have shown that R449A, when replacing R507A systems, has better heat transfer performance at higher temperatures and is suitable for refrigeration systems with higher temperature conditions.

A Simple Method for Estimating Stomatal Aperture from Temperature Measurements on Intact Leaves and Wet and Dry Artificial Reference Leaves

Environmental control in greenhouse horticulture is essential for providing optimal conditions for plant growth and achieving greater productivity and quality. To develop appropriate environmental management practices for greenhouse horticulture through sensing technologies for monitoring the environmental stress responses of plants in real time, we evaluated the relative value of the stomatal opening to develop a technology that continuously monitors stomatal aperture to determine the moisture status of plants. When plants suffer from water stress, the stomatal conductance of leaves decreases, and transpiration and photosynthesis are suppressed. Therefore, monitoring stomatal behavior is important for controlling plant growth. In this study, a method for simply monitoring stomatal conductance was developed based on the heat balance method. The stomatal opening index (SOI) was derived from heat balance equations on intact tomato leaves, wet reference leaves, and dry reference leaves by measuring their temperatures in a growth chamber and a greenhouse. The SOI can be approximated as the ratio of the conductance of the intact leaf to the conductance of the wet reference leaf, which varies from 0 to 1. Leaf temperatures were measured with infrared thermometry. The theoretically and experimentally established SOI was verified with tomato plants grown hydroponically in a greenhouse. The SOI derived by this method was consistent with the leaf conductance measured via the porometer method, which is a standard method for evaluating actual leaf conductance that mainly consists of stomatal conductance. In conclusion, the SOI for the continuous monitoring of stomatal behavior will be useful not only for studies on interactions between plants and the environment but also for environmental management, such as watering at plant production sites.

Applicability of radiant and convection time series method in coincident design day generation for radiant cooling systems

Previous studies have shown that coincident design day (CDD) can make the calculated design cooling load of an air-conditioning system more rational and accurate. The conversion process of room heat gain to cooling load in radiant cooling systems is different from that in convection cooling systems. The radiant time series method (RTSM) of generating the coincident design day is inapplicable to radiant cooling systems. In this paper, the radiant and convection time series method (RCTSM) is proposed to generate the coincident design day for radiant cooling systems. The relative deviation of design cooling load, computation time for generating coincident design days, and the correct rate are introduced to evaluate the applicability of RCTSM for generating coincident design days. Fifteen room/building characteristic parameters are taken into account to construct 10,000 simulated sample rooms for each city. Compared to the theoretical design cooling load, the relative deviations of design cooling load determined by RCTSM are generally within 7.23 %. RCTSM is suitable to calculate design cooling load and generate coincident design day for radiant cooling systems. The computation time of RCSTM for generating coincident design day is less than one of sixty-third of that of heat balance method. RCTSM can significantly enhance the efficiency in generating coincident design day. The correct rates of the coincident design days generated using RCTSM is higher than those using heat balance method. These results indicate that RCTSM is more suitable to generate the coincident design days for radiant cooling systems than heat balance method.

The dynamics of nocturnal sap flow components of a typical revegetation shrub species on the semiarid Loess Plateau, China.

The components of nighttime sap flux (En), which include transpiration (Qn) and stem water recharge (Rn), play important roles in water balance and drought adaptation in plant communities in water-limited regions. However, the quantitative and controlling factors of En components are unclear. This study used the heat balance method to measure sap flow density in Vitex negundo on the Loess Plateau for a normal precipitation year (2021) and a wetter year (2022). The results showed that the mean values were 1.04 and 2.34g h-1 cm-2 for Qn, 0.19 and 0.45g h-1 cm-2 for Rn in 2021 and 2022, respectively, and both variables were greater in the wetter year. The mean contributions of Qn to En were 79.76% and 83.91% in 2021 and 2022, respectively, indicating that the En was mostly used for Qn. Although the vapor pressure deficit (VPD), air temperature (Ta) and soil water content (SWC) were significantly correlated with Qn and Rn on an hourly time scale, they explained a small fraction of the variance in Qn on a daily time scale. The main driving factor was SWC between 40-200cm on a monthly time scale for the Qn and Rn variations. Rn was little affected by meteorological and SWC factors on a daily scale. During the diurnal course, Qn and Rn initially both declined after sundown because of decreasing VPD and Ta, and Qn was significantly greater than Rn, whereas the two variables increased when VPD was nearly zero and Ta decreased, and Rn was greater than Qn. These results provided a new understanding of ecophysiological responses and adaptation of V. negundo plantations to increasing drought severity and duration under climate changes.

Comparison of Cooling Loads of a Building in the Site with Heat Balance and Radiation Time Series Methods and Computer Aided Analysis

Recently, extensive research has been conducted on energy saving in the buildings. Cooling loads and heat gains stand out as a pivotal factor influencing energy consumption, underscoring the critical need for accurate calculations. This study aims to compare Radiation Time Series and Heat Balance methods, recognized as optimal approaches for cooling load calculations in the ASHRAE Handbook, utilizing computer software. The primary focus of this investigation was a four-floor U-type geometry primary school in Kayseri, comprising 116 spaces and 93 zones. The building was modeled using Revit software, employing the Radiant Time Series method, and IESVE software, incorporating the Heat Balance method. All relevant data inputs were defined, and subsequent cooling load calculations were executed. The outcomes reveal that Revit produces a total cooling load estimate of 0.6% lower than IESVE. In conclusion, the values derived from both RTS and HB methods for calculating the building's cooling loads exhibit noteworthy proximity, affirming the robustness of these methodologies in conjunction with computer software applications.

Analysis of thermal characteristics of building envelope structure for night storage heating

In order to understand the thermal characteristics analysis of nighttime thermal storage heating, the author proposes a study on the thermal characteristics analysis of nighttime thermal storage heating of building envelope structures. In some places, the writer will use an office room as a research object. The main purpose of the experiment is to measure, compare and analyze the surface temperature and heat flow rate of the room sample volume under two conditions: constant power 24 hour heating and night constant thermal power (12 hours) heating. In order to verify the accuracy of the dynamic thermal process of the heating room, the indoor air time variation will be performed along with the simulation results. Thermal performance parameters and characteristics of building thermal envelope heating effect of storage room were studied. The mathematical model of the thermal dynamic process of the heating room was established using the heat balance method and verified by experiments. According to the experiment, when the heating time increases from 5-12 hours, the additional heating consumption of the building heating system decreases by 500 Wh, and the additional heating consumption decreases to 19.4. In addition, it is important to change the heating time of the night-time packing model and the total heat accumulation. In addition, external wall insulation is useful in reducing additional heating consumption and building heating costs, but all heat transfer between model blocks is low. As the weather changes and the heat transfer coefficient of the external window increases, the additional amount of heat consumption and the additional value of heat consumption for heat storage of the building will increase. In the process of continuous heating operation, the additional heat consumption of the building heating system, the additional heat consumption gradually decreases, the heating equipment changes per hour, and the total heat accumulation of the night packing structure is important.

The Seasonal Variability and Environmental Factors Influencing the Transpiration of Western Juniper (Juniperus occidentalis) Saplings

There is scarce information regarding the interactions between young tree water uptake and the environment in water-limited ecosystems. This study was conducted in a semiarid rangeland ecosystem in central Oregon, Pacific Northwest Region, USA. We measured the tree transpiration of western juniper (Juniperus occidentalis) saplings using the stem heat balance (SHB) method. We analyzed the correlation between transpiration and environmental factors affecting the saplings’ water use from May to October for 2017, 2018, 2019, 2021, and 2022. The study results showed that total annual precipitation for all but one year was below the long-term (2005 to 2022) mean precipitation value of 307 mm for the study site. Significantly higher transpiration rates were observed in the wet vs. dry years. The highest monthly averaged transpiration rates (2.95 L d−1) were obtained in August during the above-average precipitation year (2017). Peak transpiration rates for the below-average precipitation years were generally reached in June or July, ranging from 0.91 to 1.65 L d−1. The seasonal response of transpiration to different environmental factors varied. For all years, vapor pressure deficit (VPD), solar radiation (SR), and air temperature (AT) showed a positive correlation with transpiration, whereas precipitation (Pr) and relative humidity (RH) indicated a negative correlation with transpiration. Soil moisture (SM) and soil temperature (ST) positively correlated with transpiration for most years. A strong association between VPD and transpiration was observed during the wettest (2017; 327 mm) and driest (2021; 198 mm) years. Results from this study add to the limited literature on sapling transpiration and can contribute to the improved management of cool-climate rangeland ecosystems through an enhanced understanding of water use by young-stage trees and its potential impacts on the water balance of restored juniper landscapes.

Experimental monitoring of CO2 hydrate slurry crystallization by heat flux rate determination in a jacketed reactor

CO2 hydrate slurries are promising phase change materials for secondary refrigeration applications. However, the difficulty of experimentally evaluating the crystallization kinetic of slurries limits their industrial use. Hydrate crystallization kinetics monitoring performs traditionally by a reactor mass balance. However, this method requires assumptions on CO2 liquid phase concentration and the hydration number. This work outlines the development of a specific method to determine kinetics thanks to the direct measure of heat flow through the reactor jacket and its evaluation compared with the mass balance method. The results of each method are then obtained by testing the two kinetic parameters of stirring speed and propeller type. The final hydrate mass fractions obtained with both methods are in good agreement, but the kinetic obtained by the mass balance method is faster than by the heat balance method.

Responses of sap flow density of two shrub species to rainfall classes on the semiarid Loess Plateau of China.

Rainfall events can determine a cascade of plant physiological and ecological processes, and there is considerable interest in the way that rainfall modifies plant water flux dynamics. The sap flow density (SF) of the planted species of Vitex negundo and Hippophae rhamnoides, on the Loess Plateau of China was monitored using the heat balance method from 2015 to 2017. The results showed that SF responded differently to rainfall classes because of the changing meteorological and soil water content (SWC) conditions. For class 1: 0.2-2 mm, SF increased by 14.36-42.93% for the two species, which were mainly attributable to the effect of solar radiation and vapor pressure deficit after rainfall. For class 2: 2-10 mm, SF remained nearly stable for V. negundo and decreased for H. rhamnoides because of the relative humidity's effect. For class 3: > 10 mm, SF increased significantly because of increased SWC and the increasing response to solar radiation. The increased percentage of SF was relatively higher for V. negundo when rainfall was less than 20 mm, while the value was higher for H. rhamnoides when rainfall was greater than 10 mm. Further, V. negundo's water potential increased at the soil-root interface (ψ0) and ψL, indicating that the plant, which has shallower roots and a coarser of leaf and bark texture, considered as anisohydric species and used precipitation-derived upper soil water to survive. The relatively consistent ψL and ψ0 for H. rhamnoides, which has deep roots and leathery leaves, indicated that this species was considered as isohydric species and insensitive to the slight change in the soil water status. The differed response patter and water use strategies between the two species showed that species as V. negundo are more susceptible to frequent, but small rainfall events, while larger, but less frequent rainfall events benefit such species as H. rhamnoides. This study quantified the effect of environmental factors for SF variation. The results could help formulate a selection process to determine which species are more suitable for sustainable management in the afforestation activities under the context of more frequent and intense rainfall events.

Experimental study on a closed-cycle Joule-Thomson cryocooler working at liquid hydrogen temperature

Because of high reliability, simplicity and no moving parts in the cold end, the Joule-Thomson (JT) cryocooler working at liquid hydrogen temperature has the potential to be used in the field of hydrogen liquefaction, liquid hydrogen storage and electronic devices cooling. However, studies on JT cryocoolers with cooling capacities above 10 W at liquid hydrogen temperature are rare. Therefore, in order to study cooling characteristics of a closed-cycle JT cryocooler working at liquid hydrogen temperature with a cooling capacity above 10 W, a laboratory prototype of a simplified JT cryocooler driven by an oil-lubricated scroll-type compressor has been built and tested. Pure hydrogen gas is used as the working fluid. The cool-down process of this closed-cycle JT cryocooler is illustrated and analyzed. The cooling temperature of 20.7 K is approached at the end of the cool-down process. Using the heat balance method, a stable cooling capacity of 10.9 W at 20.8 K is measured. The stability of temperature, pressure and mass flow rate is analyzed. Over a period of 0.5 h, the maximum differences in cooling temperature and pressure are lower than 0.1 K and 0.001 MPa, respectively. Mass flow rate fluctuation which is 0.44 mg/s has little influence on the cooling temperature.

Water Use Efficiency in Young Citrus Trees on Metalized UV Reflective Mulch Compared to Bare Ground

A precise estimation of plant water use is crucial for efficient irrigation management and understanding of plant–water interactions. Metalized-polyethylene mulch as a ground cover, combined with irrigation management, can improve water and fertilizer use, efficiency growth, and yield of young citrus trees, compared to bare ground. Thus, a study was undertaken to (i) compare daily water use, using the stem heat balance (SHB) method on ≤4-year-old citrus trees using three irrigation methods, and (ii) to determine soil moisture content, as well as total available soil water (TASW) in the irrigated zone. Three irrigation methods, regulated deficit irrigation (RDI), conventional drip irrigation (CD), and microsprinkler irrigation (MS), were applied on two sandy soils in central and southwest Florida with treatments further split between trees grown on 2.4 m mulched beds (M) and bare ground (NM) to form a factorial design. Measurements included sap flow, canopy size, leaf area index (LAI) and soil moisture. The result of this study shows greater values for the trunk cross-sectional area, canopy volume and LAI for both mulch treatments, in comparison to bare ground treatments. The sap flow data suggest that RDI resulted in higher water use than both CD and MS. The hourly sap flow was 120, 99 and 163% greater in M-RDI than M-CD, NM-CD and NM-MS, respectively. Mulched ground cover showed a higher soil moisture average at all soil layers (8-, 15- and 45-cm depth). For instance, the mulched ground cover showed higher soil moisture (37%) at a 15 cm depth at the Entisol site, followed by 30% at a 45 cm depth and 25.3% at depth 45 cm for the Spodosol site. The TASW values varied between 100 to 136% for both mulch and bare ground treatments. The irrigation systems used showed water contents close to field capacity, indicating that water was not limiting despite the different irrigation schedules. The high-water uptake is ascribed to frequent irrigation applications and pulses, and improved water distribution in the irrigated zone as a result of the mulch. These findings demonstrate the potential of metalized-polyethylene mulch and regulated drip irrigation to enhance water use efficiency.

Literature Review on Air Conditioning Heat load Analysis of a Cabin

Abstract: Air conditioning system is necessary in automobile to maintain the comfort condition. Therefore, it is important to study transient response of vehicle under real driving conditions. The Heat Balance Method (HBM) is used for estimating the heating and cooling loads which develops inside the vehicle cabin. The Load Calculation of Automobile Air Conditioning System is calculated and presented. An hourly cooling load is calculated in Tirunelveli region with respect to its latitude. Tons of refrigeration required is also found out from the cooling load calculation and a review on cooling load calculation is also presented. This study gives overall cooling load and AC power consumption which can be used by HVAC engineers to design more efficient car AC systems. Only by knowing the cooling load and source of thermal load, we can develop intelligent system to reduce AC consumption. Environmental Control System (ECS) is a generic term used in aircraft industry for maintaining the required air temperature and pressure inside passenger and crew compartment. The real challenge for an ECS is to operate and supply adequate cooling over a wide range of ground and flight conditions in a most reliable and efficient manner. The most important aspect of ECS is to know the cabin heat loads during air cooling or air heating phases. A precise calculation of aircraft heat load would be a long process requiring detailed knowledge of the aircraft structure and of the quantities involved in the mechanism of heat pick up and interchange in the cabin. This paper describes a method that may be applied in calculating the heat load for any aircraft and calculations are shown for a typical light transport aircraft under the conditions that, the cabin altitude is maintained within 0 ft to 8000 ft (2438.4m) for the aircraft altitude of 0 ft to 25000ft (7620m). The system shall be capable of maintaining temperatures within 59°F to 75°F (15°C to 30°C).

Analysis and research on the thermal system of waste incineration power generation unit based on heat balance method

The thermal system of waste incineration power generation unit is simple and small in capacity, but the original parameters are few. It needs to calculate the thermal system and derive the parameters by using the conventional heat balance method to obtain the complete thermal system parameters. In this paper, an accurate and perfect thermodynamic model of waste incineration power generation is established to solve the problems of low thermal efficiency and high unit investment cost of the waste incineration power generation. To investigate the internal relationship between the incinerator unit structure, operating parameters, waste calorific value and waste combustion process, optimize the combustion status of different incinerators burning different waste, and realize its stable and efficient operation, it is necessary to study the impact of changing operating parameters and different incinerator structures on the waste incineration process, as well as the incineration law of a single incinerator unit structure burning waste with different calorific value. Based on the two-fluid model of primary oxygen supply and secondary oxygen supply, a newly developed thermodynamic model for waste incineration engineering was developed, and the direct coupling between the reciprocating grate and the incinerator was realized in the software. Using the conventional heat balance method and constant flow calculation, the flow parameters of the thermal system under the design condition are calculated through the design pressure parameters to calculate the power generation and thermal economy index of the condition; and the relevant steam extraction flow is checked and verified. The experimental results show that the net thermal efficiency of waste incineration increases from 19. 73% to 26. 40%, and the energy utilization efficiency also increases by 0. 18%. The net thermal efficiency of the optimized integrated power generation system is always higher than that of the independent power generation system more than 0.16%. The model method used in this paper can reduce the influence of incinerator arch structure on bed combustion to a greater extent, which makes the simulation results close to reality, greatly reduces the calculation cost, and is conducive to the industrial application of simulation in the field of waste incineration.

Online temperature distribution estimation of lithium-ion battery considering non-uniform heat generation characteristics under boundary cooling

Lithium-ion batteries (LIBs) generate a lot of heat in the course of use, which will lead to a highly uneven distribution of the temperature, thus affecting the accuracy of battery modeling, parameter estimation and thermal management. In order to solve this potential threat, an on-line temperature distribution estimation method of LIB considering non-uniform heat generation under boundary cooling is proposed in this paper. Firstly, a thermal model of tab area is constructed by using lumped parameter method based on the analysis of the heat generation and heat transfer mechanism, and this tab thermal model is regarded as the first kind of boundary condition of the cell core. Secondly, a difference equation of the temperature distribution of the core area is constructed by using the heat balance method, and the boundary conditions and convection coefficient model are also deduced. Finally, a disturbance observer is designed to estimate the state and disturbance simultaneously to further improve the accuracy of temperature estimation. Additional stability analysis shows the convergence of the proposed disturbance observer. Experiments and verification demonstrate that the proposed method is effective and has better estimation performance compared with the other traditional methods under four different cycles, and the estimation error is less than 1.5 °C.