Summary
Deep borehole heat exchanger (DBHE) is attracting attention intensively owing to much more geothermal extraction, higher efficiency for heat pumps, and lesser land demand compared with ...shallow borehole heat exchanger. DBHE is usually dipped into several thousand meters in the subsurface, having a complicated heat transfer with surrounding rock–soil. However, the heat transfer characteristics below surface under different conditions are rarely studied. In this study, a numerical model considering the comprehensive effects of geothermal gradients and heat loss from inner pipe was proposed. The model was validated with experimental data and Beier analytical solution. Based on the model, the effects of primary design parameters on the heat transfer performance below surface along the pipe were investigated. The results indicate that temperature at pipe bottom increases with inlet flow rate decreasing, while the heat load cannot be extracted fully to the surface because of the heat loss of inner pipe. When the inlet flow rates decrease from 41.39 to 4.52 m3/h, the heat loss ratio increases from 25.5% to 63.7%. It is an effective way of insulating inner pipe to reduce heat loss under low inlet flow rates. Increasing the velocity in inner pipe by lessening the inner pipe diameter can also decline the heat loss well. While by this way, the increasing pumping power resulting from the higher velocity in inner pipe has to be considered. This study is significant to effective optimization of DBHE and energy conservation of buildings.
A new deep borehole heat exchanger (DBHE) numerical model with logarithmic discretization in radial direction was proposed, which can account the small distances between the DBHE and the surrounding rock–soil. The developed model considers the comprehensive effects of geothermal gradients and heat loss from inner pipe. The heat transfer along the pipe can be reflected by the temperature profiles and the specific heat load distributions, which is solved on the basis of the finite volume method.
China achieved an energy savings of 67.5 Mtce in the building sector at the end of the 11th Five-Year Plan and set a new target of 116 Mtce by the end of the 12th Five-Year Plan. In this paper, an ...improved bottom-up model is developed to assess the carbon abatement potential and marginal abatement cost (MAC) of 34 selected energy-saving technologies/measures for China's building sector. The total reduction potential is 499.8 million t-CO2 by 2030. 4.8 Gt-CO2 potential will be achieved cumulatively to 2030. By 2030, total primary energy consumption of Chinese building sector will rise continuously to 1343 Mtce in the reference scenario and 1114 Mtce in the carbon reduction scenario. Total carbon dioxide emission will rise to 2.39 Gt-CO2 and 1.9 Gt-CO2 in two scenarios separately. The average carbon abatement cost of the aforementioned technologies is 19.5 $/t-CO2. The analysis reveals that strengthening successfully energy-saving technologies is important, especially for the residential building sector. The central government's direct investments in such technologies should be reduced without imposing significant negative effects. PUBLICATION ABSTRACT
Despite increasing awareness of the biological impacts of long‐chain fatty acyl‐CoA esters (LCACoAs), our knowledge about the subcellular distribution and regulatory functions of these acyl‐CoA ...molecules is limited by a lack of methods for detecting LCACoAs in living cells. Here, we report development of a genetically encoded fluorescent sensor that enables ratiometric quantification of LCACoAs in living cells and subcellular compartments. We demonstrate how this FadR‐cpYFP fusion “LACSer sensor” undergoes LCACoA‐induced conformational changes reflected in easily detectable fluorescence responses, and show proof‐of‐concept for real‐time monitoring of LCACoAs in human cells. Subsequently, we applied LACSer in scientific studies investigating how disruption of ACSL enzymes differentially reduces cytosolic and mitochondrial LCACoA levels, and show how genetic disruption of an acyl‐CoA binding protein (ACBP) alters mitochondrial accumulation of LCACoAs.
LACSer, a genetically encoded long‐chain acyl‐CoA fluorescence sensor, generates a specific fluorescence response to long‐chain acyl‐CoA, and can be used for the ratiometric quantification of long‐chain acyl‐CoA in cells and subcellular structures. The effects of ACSL and ACBP on the biosynthesis, transport, and downstream metabolism of long‐chain acyl‐CoA can be studied.
Deep borehole heat exchangers (DBHEs) extract heat from the medium-depth geothermal energy with the depth of 2–3 km and provide high-temperature heat source for the medium-depth geothermal heat pump ...systems (MD-GHPs). This paper focuses on the heat transfer performance of DBHEs, where field tests and simulation are conducted to analyze the heat transfer process and the influence factors. Results identify that the heat transfer performance is greatly influenced by geothermal properties of the ground, thermal properties and depth of DBHEs and operation parameters, which could be classified into external factors, internal factors and synergic adjustment. In addition, the long-term operation effects are analyzed with the simulation, results show that with inlet water temperature setting at 20 °C and flow rate setting at 6.0 kg/s, the average outlet water temperature only drops 0.99 °C and the average heat extraction drops 9.5% after 20-years operation. Therefore, it demonstrates that the medium-depth geothermal energy can serve as the high-temperature heat source for heat pump systems stably and reliably. The results from this study can be potentially used to guide the system design and optimization of DBHEs.
► Energy use in office buildings in China is analyzed. ► A Dual Sector feature is found. ► The Gini Coefficient is different for each city in China.
This paper analyzed the energy consumption of ...office buildings in several provinces and municipalities directly under the control of the Central Government of China, utilizing data from the first national survey of about 4600 samples which was conducted in 2007. The Electricity Use Intensity excluding District Heating (EUI excl. DH) of different cities or provinces was analyzed. By conducting a cluster analysis, it was found that a unique “Dual Sector Distribution” feature exists in office buildings in China, compared to a “Single-peak Distribution” characteristic in Japan and the US. The research also intended to explain the possible reasons behind this phenomenon. The Lorenz Curve and Gini Coefficient methods were used as references in order to reveal the regional disparity in China. The results suggested that: (1) EUI excl. DH of office buildings in each city or province in China appeared two different groups, most of them distributed on the lower range from 33.6 to 77.5kWhe/(m2a),111kWhe means 1kWh of electricity, distinguished from 1kWh heating (illustrating as kWhh) or 1kWh cooling (kWhc). excluding district heating energy use, while some of buildings fell within a higher range from 51.8 to 107.0kWhe/(m2a). (2) The Gini Coefficient illustrated that the more developed of urbanization, the less significant of distribution difference, and the higher the EUI excl. DH of office building in China.
The building sector is one of the three major energy consumption areas and one of the main areas responsible for carbon emissions. In 2019, carbon emissions related to construction and building ...operations in China accounted for 38% of the total social carbon emissions, of which construction accounted for 16% and operations accounted for 22%. Due to its large volume and high energy consumption per unit area, public buildings account for 38% of the operating energy consumption of all buildings, that is, 8% of the total national energy consumption. At this time, the building industry must take decarbonization actions to avoid a delay in realizing carbon neutrality and an emission peak. We need to form a unified process for the implementation boundary, implementation path, and index system to build a zero-carbon implementation plan for China’s public building sector. Based on bottom-up practical cases, this paper proposes the KAYA model, which is applicable to different scales and different types of public buildings/communities, and proposes specific and feasible plans. Through the implementation of demand reduction, energy efficiency improvement, and the fully-use of renewable energy in all five clear steps, this paper promotes the implementation of decarbonization in China’s building industry.
Heavy metal contamination of soil is of increasing concern because of its potential risk to human health. In this study, two AMFs (
Rhizophagus intraradices
and
Funneliformis mosseae
) substantially ...increased the biomass of bashfulgrass in Zn-contaminated soil, even at Zn levels of up to 600 mg kg
−1
. Zn uptake in
R. intraradices
- and
F. mosseae
-mycorrhizal bashfulgrass was increased by 40-fold and 7-fold, respectively, when plants grown in Zn-contaminated (400 mg kg
−1
) soil. Elemental analysis showed that neither AMF had an effect on Zn concentration in plant tissues, including the roots and shoots. However, a significant increase of phosphorus (P) concentration was observed, suggesting the increased is from the improved use efficiency of soil nutrients by AMFs. Comparing the two AMFs, better growth performance with more biomass occurred with
R. intraradices
-inoculated bashfulgrass in Zn-contaminated soil. This is consistent with
R. intraradices
being more tolerant to Zn than
F. mosseae
, indicated by a higher colonization percentage in bashfulgrass roots. Taken together, our data indicate that AMFs possibly improve acquisition and translocation of P to promote increased biomass. Moreover, mycorrhiza did not enhance Zn accumulation in shoots and roots of bashfulgrass at the same Zn level. In the future, developing AMF (especially
R. intraradices
) inoculation of plants might be a desirable means of safe production of ornamental plants in metal-polluted soil.
Voxel-based morphometry provides an opportunity to study Alzheimer's disease (AD) at a subtle level. Therefore, identifying the important brain voxels that can classify AD, early mild cognitive ...impairment (EMCI) and healthy control (HC) and studying the role of these voxels in AD will be crucial to improve our understanding of the neurobiological mechanism of AD. Combining magnetic resonance imaging (MRI) imaging and gene information, we proposed a novel feature construction method and a novel genetic multi-kernel support vector machine (SVM) method to mine important features for AD detection. Specifically, to amplify the differences among AD, EMCI and HC groups, we used the eigenvalues of the top 24 Single Nucleotide Polymorphisms (SNPs) in a
-value matrix of 24 genes associated with AD for feature construction. Furthermore, a genetic multi-kernel SVM was established with the resulting features. The genetic algorithm was used to detect the optimal weights of 3 kernels and the multi-kernel SVM was used after training to explore the significant features. By analyzing the significance of the features, we identified some brain regions affected by AD, such as the right superior frontal gyrus, right inferior temporal gyrus and right superior temporal gyrus. The findings proved the good performance and generalization of the proposed model. Particularly, significant susceptibility genes associated with AD were identified, such as
,
,
,
and
. Some significant pathways were further explored, such as the calcium signaling pathway (corrected
-value = 1.35 × 10
) and cell adhesion molecules (corrected
-value = 5.44 × 10
). The findings offer new candidate abnormal brain features and demonstrate the contribution of these features to AD.
Alzheimer's disease (AD) is a neurodegenerative brain disease, and it is challenging to mine features that distinguish AD and healthy control (HC) from multiple datasets. Brain network modeling ...technology in AD using single-modal images often lacks supplementary information regarding multi-source resolution and has poor spatiotemporal sensitivity. In this study, we proposed a novel multi-modal LassoNet framework with a neural network for AD-related feature detection and classification. Specifically, data including two modalities of resting-state functional magnetic resonance imaging (rs-fMRI) and diffusion tensor imaging (DTI) were adopted for predicting pathological brain areas related to AD. The results of 10 repeated experiments and validation experiments in three groups prove that our proposed framework outperforms well in classification performance, generalization, and reproducibility. Also, we found discriminative brain regions, such as Hippocampus, Frontal_Inf_Orb_L, Parietal_Sup_L, Putamen_L, Fusiform_R, etc. These discoveries provide a novel method for AD research, and the experimental study demonstrates that the framework will further improve our understanding of the mechanisms underlying the development of AD.
•A dynamic simulation platform for chilled water system is constructed.•System coupling factor is defined to evaluate the coupling degree in FCU system.•Increasing system coupling factor will ...increase system delta-T loss.•Adding resistance on non-terminal branches should be avoided.
Most chilled water circulation systems with fan coil units suffer from a low temperature differential between the supplied and returned water. On-site investigation shows that the relationship between total cooling consumption and total water flow rate of real systems is different from that of single coil units mainly as a result of the interaction of the terminals. When certain terminals close their water valves, the other terminals have higher water flow rates and lower water delta-T values. This study presents a quantitative analysis of terminal coupling and its effect on system characteristics. System coupling factor is used as an indicator to describe the total degree of fan coil unit coupling in a system. To observe the effect of the system coupling factor, a dynamic simulation platform is constructed and simulation tests are performed. The results show that the higher the system coupling factor is, the larger is the total delta-T loss under partial load conditions. Based on this indicator, certain problems of system design can be reviewed from the perspective of terminal coupling.
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