Virtual surface temperature sensor for multi-zone commercial buildings

Multi-zone structure is commonly used in small commercial office buildings, retail stores and supermarket. While there is no adjacent wall between the zones, the impact of a neighbor zone on the current zone can be approximated and analyzed through the application of virtual walls. It is critical to accurately estimate the virtual wall surface temperature in order to evaluate the model uncertainty and apply improved supervisory control on multiple rooftop air-conditioning units (RTUs). We propose an innovative virtual surface temperature sensor based on system-identification to solve this challenge. The validation of the virtual temperature model is processed by the three validation criteria: goodness of fit (G), mean squared error (MSE) and coefficient of determination (R2) through off control conditions with data obtained from a building simulation platform. Further, the sensitivity analysis using the on-control three conditions (under-sizing, properly sizing and oversizing condition) is conducted for analyzing and evaluating the performance of this system-identification based virtual sensor

Development And Evaluation Of A Simplified Modeling Approach For Hydraulic Systems

This paper presents how a hydraulic system can be properly modeled for hydraulic balancing, knowledge of flow distribution, coupled simulation, and evaluation of control, etc. It focuses on water-based heating and cooling systems, which generally have high energy efficiency in design but could perform poorly in reality due to the undersensing condition and strong thermal-hydraulic coupling. The study introduces the motivation, presents the simplified modeling methodology, and illustrates the model and simulating structure. A preliminary evaluation of the method is conducted with two simple simulations. The proposed “node-branch-state” modeling approach could be easily modified, expanded and integrated into a detailed thermal model. The paper concludes with some discussions on future work

A thermo-activated wall for load reduction and supplementary cooling with free to low-cost thermal water

A building envelope serves as a thermal barrier and plays an important role in determining the amount of energy used to achieve a comfortable indoor environment. Conventionally, it is constructed and treated as a passive component in a building thermal energy system. In this article, a novel, mini-tube capillary-network embedded and thermal-water activated building envelope is proposed to turn the passive component into active, therefore broaden the direct utilization of low-grade thermal energy in buildings. With this proposed approach, low-grade thermal water at a medium temperature close to the ambient environment can be potentially utilized to either counterbalance the thermal load or indirectly heat and cool the space. With the revealing of the idea, effects of water temperature and flow rate on the envelope’s thermal performance are investigated using a transient model. The results indicate that the thermo-activated wall can be effective in stabilizing the internal surface temperature, offsetting the heat gain, and supplying cooling energy to the space in summer. Utilization of the innovation should take the cost of total energy, energy benefit and efficiency into consideration. This article illustrates how low-grade energy can be actively used as a means for achieving net-zero energy buildings

The Arabidopsis thaliana elongator complex subunit 2 epigenetically affects root development

The elongator complex subunit 2 (ELP2) protein, one subunit of an evolutionarily conserved histone acetyltransferase complex, has been shown to participate in leaf patterning, plant immune and abiotic stress responses in Arabidopsis thaliana. Here, its role in root development was explored. Compared to the wild type, the elp2 mutant exhibited an accelerated differentiation of its root stem cells and cell division was more active in its quiescent centre (QC). The key transcription factors responsible for maintaining root stem cell and QC identity, such as AP2 transcription factors PLT1 (PLETHORA1) and PLT2 (PLETHORA2), GRAS transcription factors such as SCR (SCARECROW) and SHR (SHORT ROOT) and WUSCHEL-RELATED HOMEOBOX5 transcription factor WOX5, were all strongly down-regulated in the mutant. On the other hand, expression of the G2/M transition activator CYCB1 was substantially induced in elp2. The auxin efflux transporters PIN1 and PIN2 showed decreased protein levels and PIN1 also displayed mild polarity alterations in elp2, which resulted in a reduced auxin content in the root tip. Either the acetylation or methylation level of each of these genes differed between the mutant and the wild type, suggesting that the ELP2 regulation of root development involves the epigenetic modification of a range of transcription factors and other developmental regulators

Long-term exposure to ambient fine particulate matter and fasting blood glucose level in a Chinese elderly cohort

Fasting blood glucose level is the primary indicator for the diagnosis of diabetes. We aim to conduct a longitudinal study on the association between long-term fine particulate matter (PM2.5) exposure and fasting blood glucose concentrations. We recruited and followed up 1449 participants older than 65 years of age in 2009, 2012, 2014, and 2017 in eight counties in China. Fasting blood glucose was repeatedly measured 3697 times in total among these participants. Data on annual ground-level PM2.5 concentrations with a 0.01° spatial resolution from 2005 to 2016 were used to assess exposures. An increase of 10 μg/m3 in 3-year average exposure to PM2.5 was associated with an increase of 0.146 mmol/L (95% confidence interval [CI]: 0.045, 0.248) in fasting blood glucose in all participants. The association was more pronounced among the subgroup with diabetes compared to the subgroup without diabetes (P < .05). In conclusion, Long-term PM2.5 exposure was associated with an increase in fasting blood glucose levels among elderly people. Elderly individuals with diabetes are particularly vulnerable to high level exposures of PM2.5. SUMMARY: Long-term PM2.5 exposure was associated with an increase in fasting blood glucose levels among elderly people. Elderly individuals with diabetes are particularly vulnerable to high level exposures of PM2.5. Keywords: elderly; fasting blood glucose; fine particulate matter; long-term exposur

Integrating Air Handling Units in Office Buildings for High Performance

This study investigates the thermal load features in office buildings and proposes an innovative Integrated Air Handling Unit (IAHU) concept in order to achieve energy savings with conventional office building air handling systems. The corresponding deduction of IAHU for an acceptable Indoor Air Quality (IAQ) and better energy performance is conducted. The system variables and constraints are analyzed in detail to understand the feasibility and operability of IAHU. The control logics and implementation methods are elaborated for typical system layouts. With an IAHU operation, the internal heat gain can be transferred from an interior region into an exterior region in winter. The sensible load and latent coil load can also be decoupled in mild weather. To evaluate the performance of IAHU for buildings, especially insufficiently sub-metered buildings, a simplified simulation method is proposed. The theoretical modeling process is provided. Through a case building simulation, it is found that, by converting a Two Air Handling Unit (TAHU) system into an IAHU system, about 14% of thermal energy can be saved for the case building, which is equivalent to a 3.5 MBTU/ft2 yr saving in the given climate. By transferring the internal heat gain from the interior region to the exterior region, 58% of the total savings, by applying IAHU, can be achieved in winter time and 17% in swing seasons. Another 25% savings comes from the sensible and latent coil load decoupling of using IAHU in summer mild weather

MENG 4200: Heat Transfer—A Peer Review of Teaching Project Benchmark Portfolio

The main goal of attending this course review project is to improve my teaching performance of technical courses so that both the students and I can enjoy the mutual-learning process. Teaching to me is really rewarding. I believe teaching is an art, which can be continuously improved through learning from the peers, collecting and analyzing students\u27 feedback and practice, regardless whether it is technical or practical. With good teaching, any course can be taught in a joyful manner. The specific objectives of the course portfolio include the follows: 1. Document the main materials for future refining through the documentation process of this project. I have been teaching this required course to sophomore students in three options of Architectural Engineering since 2012. Heat Transfer, as Thermodynamics and Fluid dynamics, serves a base to the advanced courses. This course is difficult to teach due to the technical characteristics. Heat transfer, including conduction, convection, radiation and multi-modes, are not tangible to the students. I prepared the class in a way revealing the concepts, equations, and their applications step-by-step. Instead of letting students be merged in lengthy texts and various complex heat transfer problems, I always start with a review on the previous lecture, then explain the concepts or deduce the equations, and provide examples. Documenting the course materials from the syllabus, homework to exams, provides me with a base of understanding the students\u27 learning process so that adjustments can be made in the future. 2. Self-evaluating my teaching performance and identifying the potentials for improvements. Students\u27 learning performance in a technical course is largely dependent on how the materials are taught. Boring repetition of textbook concepts and equations from the teacher can easily kill the students learning interest. Consequently, the teacher will lost his/her interest in teaching. I always try to constantly adapt my teaching based on the students\u27 reaction. For example, I added two more recitations to the tight schedule and reduced some theoretical deduction in the second half of the semester. Even so, I noticed that some students can not follow the teaching and digest the contents. There are rooms for improvement to make the students enjoy the learning process. 3. Serving as a foundation for developing new courses in both undergraduate and graduate level to enhance the curriculum in the school. As a junior faculty, I am eager to develop new courses focusing on building system operation where most primary energy was consumed. Starting from the scratch without the textbook and classnotes is always a challenge. Systematically collecting the materials in other technical courses and conducting self-evaluation in this project can help me identify the strengths and shortcomings in my teaching, understand the students learning preference and utilize the findings for new courses

Heat and Mass Transfer Performance Analysis and Cooling Capacity Prediction of Earth to Air Heat Exchanger

A great portion of the primary energy is consumed by space heating and cooling in buildings. The need for utilizing more renewable energy in the building sector remains critical for ensuring the energy and environment sustainability. Geothermal energy is one of the renewable energy sources that we have an easy access to for supplying low-grade thermal energy with a low impact on the environment. The methods of utilizing geothermal energy for buildings include such as ground source heat pumps and earth to air heat exchangers (EAHEs). In this paper we presented the comprehensive performance analysis and deduced an easy-to-apply regression model for predicting the cooling capacity of an EAHE. A one-dimensional steady-state control volume model was developed and applied to simulate the performance of the EAHE. It couples both heat and mass transfer between the air and the tube. The model was calibrated by comparing against the experimental data from an existing renewable energy testing facility. After the calibration, six factors, namely the air temperature, the air relative humidity, the air velocity at the inlet of EAHE, the tube surface temperature, and the tube length and diameter on the performance were analyzed using the calibrated model. The polynomial regression models for predicting the cooling capacities including total, sensible and latent cooling capacity with high accuracy were obtained. The easy-to-apply formulas can be of great use in the design and application of EAHEs