14 research outputs found
Heat Transfer of Helix Energy Pile: Part 2āNovel Truncated Cone Helix Energy Pile
Owing to the fact that severe thermal interferences exist in the radial and generatrix directions of the traditional cylinder helix energy pile due to the limited thermal heat capacity of the pile and small ratio between coil pitch and radius of pile, therefore, a novel truncated cone helix energy pile (CoHEP) is presented to weaken the thermal interferences and improve the heat transfer efficiency. Further, both the analytical solution model and numerical solution model for CoHEP are built to discuss the dynamic characteristics of thermal interferences and heat transfer performance. The results indicate that the thermal interference of CoHEP is dynamic. The thermal interference in the upper part of the CoHEP is much smaller than the traditional CyHEP. And in general the heat flux per unit pipe length of the novel CoHEP is larger than that of the traditional CyHEP. Heat flux per unit pipe length of the CoHEP increases linearly with inlet water temperature. For the same inlet water temperature, the thermal short circuit is serious at the bottom of the CoHEP, and itās weak in the upper part of CoHEP. Also itās obvious that as the inlet water temperature increases, the thermal short circuit becomes more serious
Heat Transfer of Helix Energy Pile: Part 1: Traditional Cylinder Helix Energy Pile
Helix energy pile (HEP) is a new popular ground heat exchanger that has the advantages of large heat exchange rate and low initial cost. As for the traditional helix energy pile, the tube is wound on the cylindrical wall, which is called the cylinder helix energy pile (CyHEP). Further, both analytical solution model and numerical solution model for CyHEP are built to discuss the dynamic characteristics of thermal interferences and heat transfer performance. The results indicate that four heat exchange stages for the spiral pile geothermal heat exchanger along the fluid flow direction are revealed: inlet heat exchange stage, grout thermal short-circuiting stage, small temperature difference stage and outlet heat exchange stage. Each stage has corresponding heat transfer characteristics, and reducing the length of small temperature difference stage and increasing the other stages would enhance the heat exchange of spiral geothermal ground heat exchanger. As the pile diameter increases, the heat transfer per unit tube length decreases, and the heat exchange per unit pile depth increases. As the pile depth increases, the heat transfer per unit tube length and the heat exchange per unit pile depth are reduced. And as the pitch increases, the heat transfer per unit tube length increases, and the heat exchange per unit pile depth decreases
Atomic Insights into Distinct Hormonal Activities of Bisphenol A Analogues toward PPARĪ³ and ERĪ± Receptors
Bisphenol
A analogues (BPAs) belong to a wide variety of large
volume chemicals with diverse applications yet emerging environmental
concerns. Limited experimental data have demonstrated that BPAs with
different halogenation patterns distinctly affect the agonistic activities
toward proliferator-activated receptor (PPAR)ĀĪ³ and estrogen
receptors (ER)ĀĪ±. Understanding the modes of action of BPAs toward
different receptors is essential, however, the underlying molecular
mechanism is still poorly understood. Here we probed the molecular
recognition process of halogenated BPAs including TBBPA, TCBPA, BPAF,
BPC, triBBPA, diBBPA, and monoBBPA toward PPARĪ³ and ERĪ±
by molecular modeling, especially the impact of different halogen
patterns. Increasing bromination at phenolic rings of BPAs was found
highly correlated with electrostatic interactions (<i>R</i><sup>2</sup> = 0.978 and 0.865 toward PPARĪ³ and ERĪ±,
respectively) and van der Waals interactions (<i>R</i><sup>2</sup> = 0.995 and 0.994 toward PPARĪ³ and ERĪ±, respectively).
More halogenated phenolic rings at 3,5-positions of BPAs increase
the shielding of the hormonally active phenolic OH and markedly decrease
electrostatic interactions favorable for agonistic activities toward
PPARĪ³, but unfavorable for agonistic activities toward ERĪ±.
The halogenation at the phenolic rings of BPAs exerts more impact
on molecular electrostatic potential distribution than halogenation
at the bridging alkyl moiety. Different halogenations further alter
hydrogen bond interactions of BPAs and induce conformational changes
of PPARĪ³ ligand binding domain (LBD) and ERĪ± LBD, specifically
affecting the stabilization of helix H12 attributable to the different
agonistic activities. Our results indicate that structural variations
in halogenation patterns result in different interactions of BPAs
with PPARĪ³ LBD and ERĪ± LBD, potentially causing distinct
agonistic/antagonistic toxic effects. The various halogenation patterns
should be fully considered for the design of future environmentally
benign chemicals with reduced toxicities and desired properties
Thermal Performance Optimization Simulation Study of a Passive Solar House with a Light Steel Structure and Phase Change Walls
Phase change materials are used in passive solar house construction with light steel structure walls, which can overcome the problems of weak heat storage capacity and poor utilization of solar heat and effectively solve the thermal defects of light steel structure walls. Based on this, on the basis of preliminary experimental research, this study further carried out theoretical analysis and simulation research on the thermal performance of a light steel structure passive solar house (Trombe form) with PCM walls. Through the heat balance analysis of heat transfer in the heat collecting partition wall, the theoretical calculation formula of the phase change temperature of the PCM was obtained, and it verified theoretically that the phase change temperature value should be 1ā3 Ā°C higher than the target indoor air temperature. The evaluation index āaccumulated daily indoor temperature offset valueā was proposed for evaluating the effect of phase change materials on the indoor temperature of the passive solar house, and āEnergyPlusā software was used to study the influence of the phase change temperature, the amount of material, and the thickness of the insulation layer on the indoor air temperature in a natural day. The results showed that there was a coupling relationship among the performance and between of the thickness of the PCM layer and the phase change temperature. Under typical diurnal climate conditions in the northern Tibetan Plateau of China, the optimal combination of the phase change temperature and the layer thickness was 17 Ā°C and 15 mm, respectively. Especially at a certain temperature, excessive increases in the thickness of the phase transition layer could not improve the indoor thermal environment. For this transition temperature, there exists an optimal transition layer thickness. For a Trombe solar house, the thickness of the insulation layer has an independent impact on indoor temperature compared to other factors, which has an economic value, such as 50 mm in this case. In general, this paper studied the relationship between several important parameters of the phase change wall of a solar house by using numerical simulation methods and quantitatively calculated the optimal parameters under typical meteorological conditions, thus providing a feasible simulation design method for similar engineering applications
Study on Heat Storage Performance of Phase Change Reservoir in Underground Protection Engineering
In view of the main problems of the condensing heat discharge modes of the existing underground air-conditioning system, the technical scheme of using phase change heat storage modules to improve the heat storage capacity of the reservoir is proposed. By establishing a 3D flow and transient heat transfer model of the phase change reservoir, the effects of thermal property parameters, package size and arrangement of the phase change heat storage modules on the heat storage performance of the phase change reservoir were quantitatively analyzed based on three indexes: heat storage capacity per volume Δq, guaranteed efficiency coefficient η and slope of temperature rise per unit load ε. The results show that when the phase change temperature is 29 °C (23 °C increased to 33 °C) and the latent heat value is 250 kJ/kg (100 kJ/kg increased to 250 kJ/kg), Δq (110.92 MJ/m3, 112.83 MJ/m3) and η (1.22, 1.24) under both conditions are at their most, respectively, indicating that the phase change temperature should be less than 4 °C at the outlet temperature of the reservoir, and phase change materials with a high latent heat should be selected in engineering design whenever possible. When the size of the phase change module is 150 mm × 20 mm and the phase change reservoir adopts four intakes, ε (0.259, 0.244) under both conditions is the smallest, indicating that increasing the area of the phase change heat storage module and the fluid and increasing the inlet disturbance of the reservoir can enhance its heat storage capacity
Thyroid Disruption by Bisphenol S Analogues via Thyroid Hormone Receptor Ī²: <i>in Vitro</i>, <i>in Vivo</i>, and Molecular Dynamics Simulation Study
Bisphenol
S (4-hydroxyphenyl sulfone, BPS) is increasingly used as a bisphenol
A (BPA) alternative. The global usage of BPS and its analogues (BPSs)
resulted in the frequent detection of their residues in multiple environmental
media. We investigated their potential endocrine-disrupting effects
toward thyroid hormone receptor (TR) Ī². The molecular interaction
of BPSs toward TRĪ² ligand binding domain (LBD) was probed by
fluorescence spectroscopy and molecular dynamics (MD) simulations.
BPSs caused the static fluorescence quenching of TRĪ² LBD. The
100 ns MD simulations revealed that the binding of BPSs caused significant
changes in the distance between residue His435 at helix 11Ā(H11) and
residue Phe459 at H12 in comparison to no ligand-bound TRĪ² LBD,
indicating relative repositioning of H12. The recombinant two-hybrid
yeast assay showed that tetrabromobisphenol S (TBBPS) and tetrabromobisphenol
A (TBBPA) have potent antagonistic activity toward TRĪ², with
an IC<sub>10</sub> of 10.1 and 21.1 nM, respectively. BPS and BPA
have the antagonistic activity with IC<sub>10</sub> of 312 and 884
nM, respectively. BPSs significantly altered the expression level
of mRNA of TRĪ² gene in zebrafish embryos. BPS and TBBPS at environmentally
relevant concentrations have antagonistic activity toward TRĪ²,
implying that BPSs are not safe BPA alternatives in many BPA-free
products. Future health risk assessments for TR disruption and other
adverse effects should focus more on the structureāactivity
relationship in the design of environmentally benign BPA alternatives
Single-Beam Acoustic Tweezer Prepared by Lead-Free KNN-Based Textured Ceramics
Acoustic tweezers for microparticle non-contact manipulation have attracted attention in the biomedical engineering field. The key components of acoustic tweezers are piezoelectric materials, which convert electrical energy to mechanical energy. The most widely used piezoelectric materials are lead-based materials. Because of the requirement of environmental protection, lead-free piezoelectric materials have been widely researched in past years. In our previous work, textured lead-free (K, Na)NbOā (KNN)-based piezoelectric ceramics with high piezoelectric performance were prepared. In addition, the acoustic impedance of the KNN-based ceramics is lower than that of lead-based materials. The low acoustic impedance could improve the transmission efficiency of the mechanical energy between acoustic tweezers and water. In this work, acoustic tweezers were prepared to fill the gap between lead-free piezoelectric materials research and applications. The tweezers achieved 13 MHz center frequency and 89% ā6 dB bandwidth. The ā6 dB lateral and axial resolution of the tweezers were 195 Ī¼m and 114 Ī¼m, respectively. Furthermore, the map of acoustic pressure measurement and acoustic radiation calculation for the tweezers supported the trapping behavior for 100 Ī¼m diameter polystyrene microspheres. Moreover, the trapping and manipulation of the microspheres was achieved. These results suggest that the KNN-based acoustic tweezers have a great potential for further applications.Science, Faculty ofNon UBCReviewedFacultyResearcherOthe