Cavity Temperature Research Articles

Strip cooling control for flexible production of galvanized flat steel

The work is devoted to the problem of flexible small-scale production of galvanized steel of various sizes on a continuous hot-dip galvanizing unit with varying productivity. The main focus is on the heat treatment of steel strip, the requirements for which limit productivity. In conditions of disturbances, it is necessary to proactively control the heat treatment using models, or to reduce the speed of the strip to ensure that the requirements are met. Unlike most of the works that focus on heat control, this work focuses on strip cooling. Based on the analysis of production data of the Magnitogorsk Iron and Steel Works, it is shown that violation of the cooling requirements leads to the appearance of defects in the zinc coating. Dependence of the probability of defects occurrence on the strip temperature is given. Problems of cooling predictive control are formulated using models in the absence of temperature control of the cooling section cavity. For each of the tasks, the model structure and the method of its tuning are determined according to the data accumulated over a significant period of the unit operation under conditions of uncontrolled systematic disturbances. The structure of the cooling control system is proposed by estimation of the cooling section cavity temperature as a controlled variable. The temperature estimate is determined from the model. The lack of measurement of the cooling section cavity temperature is not a problem then varying productivity. The results of the models tuning are presented according to the data of the Magnitogorsk Iron and Steel Works continuous hot-dip galvanizing unit. The proposed structures of the models and methods for their adjustment can be applied in the development of models for metal heating in furnaces.

Environmental impacts on diapause and survival of the alfalfa leafcutting bee, Megachile rotundata

Megachile rotundata exhibits a facultative prepupal diapause but the cues regulating diapause initiation are not well understood. Possible cues include daylength and temperature. Megachile rotundata females experience changing daylengths over the nesting season that may influence diapause incidence in their offspring through a maternal effect. Juvenile M. rotundata spend their developmental period confined in a nesting cavity, potentially subjected to stressful temperatures that may affect diapause incidence and survival. To estimate the impact of daylength and nest cavity temperature on offspring diapause, we designed a 3D printed box with iButtons that measured nest cavity temperature. We observed nest building throughout the season, monitored nest cavity temperature, and followed offspring through development to measure diapause incidence and mortality. We found that daylength was a cue for diapause, and nest cavity temperature did not influence diapause incidence. Eggs laid during long days had a lower probability of diapause. Siblings tended to have the same diapause status, explaining a lot of the remaining variance in diapause incidence. Some females established nests that contained both diapausing and nondiapausing individuals, which were distributed throughout the nest. Nest cavities reached stressful temperatures, which decreased survival. Mortality was significantly higher in nondiapausing bees and the individuals that were laid first in the nest. In conclusion, we demonstrate a maternal effect for diapause that is mediated by daylength and is independent of nest box temperature.

Folded double-skin façade (DSF): in-depth evaluation of fold influence on the thermal and flow performance in naturally ventilated channels

ABSTRACT Numerous studies have only focused on vertical air channel performance, but there is still a need to perform in-depth research on the flow and heat transfer characteristics of atypical double skin façade (DSF) such as folded cases. A 2D steady-state numerical study was conducted using ANSYS-Fluent 18 to evaluate the impact of four inclination angles and fold positions on DSF thermal performance. The simulation data were compared with a typical validated vertical DSF as the base case. The folded DSFs could decrease the average cavity and surface temperature by 2.4 °C through improving natural convection. The folded cases enhanced the airflow rate up to 27% higher than the base case supporting the folded geometries for building integrated photovoltaic (BIPV) DSF application.

Electrospun Chitosan/Silver Doped-Hydroxyapatite Nano-Fibers on Thermal Conductivity Modified Si<sub>3</sub>N<sub>4</sub> Ceramics with Different Sintering Cooling Rate

Dental implants are exposed to cycle loadings and thermal changes. The thermal properties of the materials in dentistry are important in terms of the biological changes that these materials will create in living tissues. The normal temperature of the oral cavity varies between 32-37℃, while eating, it can vary between 0-80℃ with hot-cold foods which led to the trauma and implant deteriorations. Si₃N₄ ceramic is a good candidate to solve these problems due to its inertness, high fracture toughness, strength, high thermal shock resistance and low density. Also, the surface modification of Si₃N₄ is important to enhance the interaction between the implant and bone. In recent years, biodegradable organic biomaterials as CTs (CTs) and silver doped hydroxyapatite (HAPs) combinations have a great attention to improve the Si₃N₄ effectiveness. In this study, MgO, SiO₂, and Y₂O₃ included substrates were fabricated for fast and slow cooling rate during sintering in dental applications. CTs/HAPs fibers were coated with the electrospinning method to develop a modified Si₃N₄ substrate. The crystal structure, microstructure and thermal diffusivity measurement of the substrates and spun surfaces were characterized with XRD, SEM and Laser Flash Method. From the results, the higher density (3.25g/cm³) and thermal conductivity (46.35W/mK) for Si₃N₄ were observed for the fast cooling process during sintering compared with the slow cooling process (3.22g/cm³ and 44.60 W/mK). The hardness and strength of the fast cooled substrate were measured as 1350 HV and 1800 MPa which are greater than the slowly cooled samples (1190 HV, 1670 MPa). CTs /HAPs fibers are homogeneously deposited with electrospinning on the surface of the fast cooled Si₃N₄ substrate to develop the surface functionality. This functionalized substrate can be a candidate in dental applications.

Comparison Analysis of Temperature Treatment on Cutleaf Groundcherry’s Leaf and Stem

The mouth has a normal microflorane of bacteria as the body's defense. Streptococcus mutans bacteria arebacteria that colonize the surface of teeth which have a role in the formation of dental caries. The leaves ofciplukan (Physalis angulata L.) are rich in polyphenols, alkaloids, and flavonoids which are reported to havequite good antimicrobial activity. The aim of this research was to determine the effect of ethanol extract ofciplukan leaves and stalks mouthwash on Streptococcus mutans bacteria. This rese arch method is purelylaboratory experimental using Streptococcus mutans bacteria culture. The antibacterial power test used theliquid dilution method which was then followed by solid dilution with an incubation period of 28 ° C. Thestatistical analysis test used a descriptive test. The results showed that the ethanol extract of the leaves andstems of ciplukan (Physalis angulata L.) had a minimum inhibitory level (MIC) and a minimum kill rate(MBC) at the same concentration, namely 15%. The temperature of the human oral cavity in cold places tendsto change because the mouth is very close to the outside environment, so this mouthwash can berecommended to minimize bacterial growth in cold areas..

Transient heating in fixed length optical cavities for use as temperature and pressure standards

Optical refractometry techniques enable realization of both pressure and temperature directly from properties of the gas. The NIST refractometer, a fixed length optical cavity (FLOC) has previously been evaluated for operation as pressure standard, and now in this paper, is evaluated for the feasibility of operation as a primary temperature standard as well. The challenge is that during operation, one cavity is filled with gas. Gas dynamics predicts that this will result in heating which in turn will affect the cavity temperature uniformity, impeding the ability to measure the gas temperature with sufficient accuracy to make the standard useful as a primary standard for temperature or pressure. Temperature uniformity across the refractometer must be less than 0.5 mK for measurements of the refractivity to be sufficiently accurate for the FLOC. This paper compares computer modeling to laboratory measurements, enabling us to validate the model to predict thermal behavior and to accurately determine the measurement uncertainty of the technique. The results presented in this paper show that temperature of the glass elements of the refractometer and ‘thermal-shell’ copper chamber are equivalent to within 0.5 mK after an equilibration time of 3000 s (when going from 1 kPa to 100 kPa). This finding enables measurements of the copper chamber to determine the gas temperature to within an uncertainty (k = 1) of 0.5 mK. Additionally, the NIST refractometer is evaluated for feasibility of operation as temperature standard.

The Feasibility of an Internal Gas-Assisted Heating Method for Improving the Melt Filling Ability of Polyamide 6 Thermoplastic Composites in a Thin Wall Injection Molding Process.

In thin wall injection molding, the filling of plastic material into the cavity will be restricted by the frozen layer due to the quick cooling of the hot melt when it contacts with the lower temperature surface of the cavity. This problem is heightened in composite material, which has a higher viscosity than pure plastic. In this paper, to reduce the frozen layer as well as improve the filling ability of polyamide 6 reinforced with 30 wt.% glass fiber (PA6/GF30%) in the thin wall injection molding process, a preheating step with the internal gas heating method was applied to heat the cavity surface to a high temperature, and then, the filling step was commenced. In this study, the filling ability of PA6/GF30% was studied with a melt flow thickness varying from 0.1 to 0.5 mm. To improve the filling ability, the mold temperature control technique was applied. In this study, an internal gas-assisted mold temperature control (In-GMTC) using different levels of mold insert thickness and gas temperatures to achieve rapid mold surface temperature control was established. The heating process was observed using an infrared camera and estimated by the temperature distribution and the heating rate. Then, the In-GMTC was employed to produce a thin product by an injection molding process with the In-GMTC system. The simulation results show that with agas temperature of 300 °C, the cavity surface could be heated under a heating rate that varied from 23.5 to 24.5 °C/s in the first 2 s. Then, the heating rate decreased. After the heating process was completed, the cavity temperature was varied from 83.8 to about 164.5 °C. In-GMTC was also used for the injection molding process with a part thickness that varied from 0.1 to 0.5 mm. The results show that with In-GMTC, the filling ability of composite material clearly increased from 2.8 to 18.6 mm with a flow thickness of 0.1 mm.

Experimental manipulation of cavity temperature produces differential effects on parasite abundances in blue tit nests at two different latitudes.

Although different predictive models forecast that climate change will alter the distribution and incidence of parasitic diseases, few studies have investigated how microclimatic changes may affect host-parasite relationships. In this study, we experimentally increased the temperature inside nest boxes of the blue tit Cyanistes caeruleus during the nestling period at two different latitudes (central Spain and central Germany) to determine its effect on parasite abundance. The two localities have contrasting climate conditions: the southern one in Spain is warmer and drier than the northern one in Germany. Consistent with this, we observed that the parasitic fauna in nests at the two localities differs. The flea species Ceratophyllus gallinae was more abundant in the northern locality, while the blowfly species Protocalliphora azurea and biting midge species of the genus Culicoides were more abundant in the southern one, as were blood parasites. Moreover, dermanyssid mites and blackflies (Simuliidae) were observed only in the southern locality. The temperature inside nest boxes was increased using heat mats placed underneath the nest material during the nestling period (day 3 to day13 post-hatching). Compared with control nests, the average temperature in heated nests increased by 2.24 °C and 1.35 °C at night in Spain and Germany, respectively. Consequently, the average relative humidity in heated versus control nests decreased 4.93 and 0.82 units in Spain and Germany, respectively. The abundance of blowfly pupae in the heated nests was significantly lower than that of control nests at both localities. The abundance of larval fleas was also lower in the heated nests, but only at the Spanish locality. Infection by the blood parasites Haemoproteus/Plasmodium was higher in males attending the heated nests in Germany, and the control nests in Spain. Moreover, both male body mass and nestling wing length were negatively related to the abundance of larval fleas. In conclusion, our results indicate that increased temperature at the nestling stage may affect the fitness of blue tits by altering parasite prevalence rates.

Factors affecting the performance of ventilation cavities in highly insulated assemblies

The article presents experimental studies of typical Finnish highly insulated (HI) envelopes with thermal resistance values ( R value) for the wall and roof inside the ventilation cavity between 7.7 and 8.1 m2K/W and 13 m2K/W, respectively. The conditions in the ventilation cavities were studied by using typical and increased R values for the exterior part of the cavity, which were 0.18 m2K/W and 1.57 m2K/W in the walls, and 0.13 m2K/W and 2.13 m2K/W for the roof. With higher exterior R values of 1.57 m2K/W and 2.13 m2K/W, the cavity temperature increased only after closing the inlet gap of the cavities. If the cavity inlet was closed, the restriction of the outlet gap from 20–25 mm to 10 mm had no significant effect on the temperatures. A closed ventilation inlet resulted in increased absolute humidity in the cavity, which indicates that the restriction of cavity ventilation should be made with care to avoid impairing the drying-out ability. The computational analysis showed that the optimal air change rates in the wall and roof cavities of HI structures were 4–40 1/h and 20 1/h, respectively. The conventional 22-mm-thick wood cladding enables safe cavity conditions in HI walls if the vapor barrier is vapor tight and other moisture sources are low. A lower heat flux and additional heat loss caused by cloudless sky at night support the observation that HI roofs have a higher moisture risk. In HI roofs, a conventional exterior R value of 0.13 m2K/W should at least be increased to the range of 0.3–0.4 m2K/W, which is achieved, for example, by a 20-mm-thick mineral wool board under the roofing. The use of mold-resistant materials in the ventilation cavity is recommended to mitigate the possible ramifications of the moisture behavior of HI roofs.

Characterization of process and machine dynamics on the precision replication of microlens arrays using microinjection moulding

Injection moulding has shown its advantages and prevalence in the production of plastic optical components, the performance and functionality of which rely on the precision replication of surface forms and on minimizing residual stress. The present work constitutes a systematic and comprehensive analysis of practical microlens arrays that are designed for light-field applications. Process parameters are screened and optimized using a two-stage design of experiments approach. Based on in-line process monitoring and a quantitative and qualitative evaluation being carried out in terms of geometric accuracy, surface quality and stress birefringence, the replication is shown to relate directly to machine settings and dynamic machine responses. The geometric accuracy and stress birefringence are both largely associated with screw displacement and peak cavity pressure during the packing stage, while surface quality is closely related to cavity temperature. This study provides important insights and recommendations regarding the overall replication quality of microlens arrays, while advanced injection moulding solutions may be necessary to further improve the general replication quality.

Prediction of the sealing flow effect on the temperature drop characteristics of a pre-swirl system in an aero-engine

Abstract The sealing flow will inevitably affect the cooling airflow quality in a second air system of an aero-engine. In this study, theoretical derivation and numerical simulation were conducted to establish a modified mixing model that considers both the torque and the source of the mixing flow. Then, the effect of the sealing flow can be evaluated using the modified mixing model. The results demonstrate that the effects of the sealing outflow on the flow and temperature characteristics of the pre-swirl system are weak when the air supply mass flow rate and pressure are fixed. However, the effects of the sealing inflow are significant. When the inner sealing inflow mass flow rate is increased from 0 to 20%, the temperature drop effectiveness is decreased by 31.3%. The temperature drop effectiveness is decreased by 29.2% as the inner sealing inflow temperature rises by 37 K. Then, the temperature drop effectiveness is increased by 15.6% as the inner sealing inflow swirl ratio is increased from 0 to 0.8. The results of the modified mixing model are in satisfactory agreement with the numerical results, which show a maximum temperature drop deviation of 7.22%. Compared with the previous method, the prediction accuracy of the pre-swirl cavity temperature drop can be increased by 22.28%.

On thermally corrugated porous enclosure (TCPE) equipped with casson liquid suspension: Finite element thermal analysis

The hybrid meshed computational analysis is carried to examine the untapped partially heated flow field in corrugated enclosure. The enclosure is rooted with porous medium and equipped with non-Newtonian liquid. The fluid flow is attain by considering the free convection. The uniformly heated Y-shaped fin is installed at bottom wall of cavity. Both right and left walls of enclosure are taken cold while the upper walls are carried adiabatic. The extreme triangular ribs at bottom walls are taken cold while second and third ribs are taken uniformly heated as Y-shaped fin. The flow field is mathematically formulated and solved by using Finite Element Method (FEM) in the presence of hybrid meshing. Modeling of non-Newtonian fluid in a cavity yields Rayleigh number, Casson fluid parameter and Darcy number. The quantities of interest includes Casson fluid stream function, Casson fluid temperature, horizontal Casson fluid velocity, vertical Casson fluid velocity and Nusselt number. Therefore, the said quantities are examined in the light of flow controlling parameters. The outcomes are shared with the help of stream functions, isotherms, and line graph study for horizontal and vertical velocities, and heat transfer rate. It is observed that the presence of Y-shaped fin results enhancement in heat transfer rate. Further, the variation of Casson fluid temperature in cavity is found directly proportional to Rayleigh number.

Simulation of melt temperature on quality of Pepsodent toothbrush products in injection molding process using Ansys software

Shrinkage is a defect in the form of a change in the dimensions of the product as a result of the injection molding process. Cooling mold is one of the factors that influence shrinkage product defects. Cooling the mold is done using a fluid medium (water cooling). The test was carried out using polypropylene material with constant parameter set-up such as injection time of 2 seconds, injection pressure of 10 MPa, coolant temperature of 22, 24, and 26 °C and melt temperatures of 190, 200 and 210 °C. Simulation uses Ansys transient software using the finite element method to analyze the average temperature in the product cavity. Simulation was using Pepsodent toothbrush products. Simulation result shows the best product quality with a product quality value produces a fill time value of 3.19 seconds with a predictive quality of 68.5% and has a weld line of 0.0115 °, a cooling time of 13.8 seconds and a shrinkage value of 0.008 mm. Simulation results show that the optimal product quality values are found in the set-up parameters of 24 °C coolant temperature, 200 °C melt temperature and 41.3 °C mold temperature. Product quality safety factor indicates that the product is in a good category. This means that the value of product quality is influenced by the mold cooler temperature and along with the increase in the mold temperature, which causes the mold cooling temperature is not constant.

Defect analysis during vacuum sintering of large Nd: YAG laser ceramics by FEM

Large-sized Nd: YAG laser transparent ceramics have great potential as the gain medium in the high-power laser devices for military and industry due to the superior thermal conductivity and optical property. However, some defects of large-sized ceramics such as deformation and fracture sometimes occur during sintering process. The real-time characterization of thermodynamic properties in the high-temperature sintering (> 1750 °C) is very difficult. It leads to unclear reasons of sintering defect. Therefore, in this work, combined with sintering systems and experiments, the thermal distribution, stress, and strain of sintered bodies were analyzed by finite element method (FEM) with non-uniform density and temperature field assumptions. For Φ15 × 220 mm ceramic rod, the order of factors affecting the thermal stress was the temperature inhomogeneous (28.29 MPa) > density gradient (15.34 MPa) > the cooling rate (11.7 MPa). The order of factors affecting the strain was also the same: inhomogeneous temperature in furnace cavity > uneven density > the cooling rate under our sintering system, and the maximum deformation was at the middle part of ceramic rod. In addition, the fracture at random position could be considered as the microcrack inside the green body. Therefore, the quality of green body directly affected the formation of ceramic defects in later sintering. These results are crucial for controlling the defects in large-sized laser ceramics preparation.

The modified optical part of a pyrometer used for calibrating tungsten-rhenium thermocouples

The provision of technological processes with modern techniques for measuring temperature is a challenging issue. For solving this problem there need to be formulated specific requirements for the optical part of the pyrometer, intended for measuring the temperature in the measurement cavity of the installation used for calibrating tungsten-rhenium thermocouples up to a temperature of 2,200 °С. In accordance with these requirements, in mass produced “Termokont” pyrometer, its optical part has been modified and experimentally investigated.

Естественная конвекция в замкнутой полости с реберной структурой при наличии неравномерного температурного профиля на вертикальной стенке

The development of energy instrumentation, electronic industry and energy in general is inextrica-bly linked with the intensification of heat and mass transfer occurring in the base units and aggre-gates of energy systems. One of the approaches to solving this problem is to create an extended heat transfer surface by introducing a rib structure or porous inserts. This work is devoted to math-ematical modeling of natural convection in an enclosure in the presence of a rib structure and non-uniform temperature profile on one of the vertical walls. The governing partial differential equa-tions written using dimensionless non-primitive variables “stream function – vorticity – tempera-ture” based on the Boussinesq approximation, in combination with initial and boundary conditions, have been worked out on the basis of the finite difference method. The developed computational model was varified using the mesh independence test and benchmark problems solved by other au-thors. Numerical investigations of unsteady natural convection of viscous fluid in a cavity with a variable temperature on the left wall under an influence of a rib structure have been carried out for the following values of governing parameters: Pr = 0.71, 103 < Ra < 106, and the number of ribs varied from one to three. Distributions of streamlines and isotherms, as well as the dependences of the average Nusselt number and average cavity temperature, were obtained for a steady mode. As a result of the analysis, it has been found that the addition of solid ribs allows to enhance the heat transfer for low Rayleigh numbers, while for Ra  105 one can find an attenuation of convective heat transfer. A growth of the fins heat conductivity characterizes the heat transfer enhancement.

Habitat use of adult Pacific bluefin tuna Thunnus orientalis during the spawning season in the Sea of Japan: evidence for a trade-off between thermal preference and reproductive activity

To examine the habitat usage of adult Pacific bluefin tuna (PBF), electronic tagging was conducted in the Sea of Japan during May and June of 2012-2017. Archival tags were internally implanted and pop-up satellite archival transmitting tags were deployed; data on the horizontal movements and diving behaviours of 36 individual PBF were successfully retrieved. In the summer spawning season, the tagged PBF were concentrated near Sado Island and Oki Island in the Sea of Japan, and they were distributed widely to the southwest (near Tsushima Island) or northeast (near the Tsugaru Strait) in the autumn and winter. We obtained the first long-term tracking record (246 d) for adult PBF, and this individual exhibited residency in a known spawning region during the spawning season in the proximity of warm-core eddy features. This fish spent most of the daytime below the thermocline between 30 and 150 m depths where the surface ambient temperature was 26.0 ± 1.5°C, but at night it ventured into the warm surface layer. Its whole-body heat transfer coefficient increased when it experienced warm waters (≥24°C), which we suggest is a physiological response to avoid overheating. The mean peritoneal cavity temperature was only 1.8°C higher than the ambient temperature, compared with 6.9°C higher during the cooler autumn-winter period. Our hypothesis is that the warm surface temperatures found in the spawning grounds induce a physiology-reproduction trade-off in adult PBF, which must behaviourally and physiologically thermoregulate their body temperature to gain spatial and temporal access to oceanographic conditions that may promote larval survivorship and growth.

Rapid High-Performance Liquid Chromatography Method for Levodopa Quantitation at Low UV Wavelength: Application of Pharmacokinetics Study in Rat Following Intranasal Delivery.

Levodopa is widely administered orally in clinical treatment of Parkinson's disease; however, due to levodopa various oral absorption and low bioavailability, intranasal delivery seems to be a suitable alternative route of administration. Pluronic F-127 is a thermosensitive polymer, which can form gel at nasal cavity temperature and increase drug residence time. In this study, a rapid High Performance Liquid Chromatography (HPLC) method was validated in presence of internal standard to determine pharmacokinetic parameters following levodopa administration to rats in three different intravenous solution, intranasal solution and intranasal thermosensitive gel groups. A precised (96.7%) and accurate (95.0%) HPLC method was validated at low UltraViolet (UV) wavelength of 208nm that showed limit of detection and limit of quantitation of 59 and 177ng/mL, respectively. Specificity results showed no interference for levodopa with endogenous serum materials, and serum extraction efficacy was 93%. Pharmacokinetic parameters including bioavailability of 75 and 85% with mean residence time of 78 and 94min were estimated for intranasal solution and thermosensitive gel using the validated HPLC method, which indicated that levodopa nasal gel may be a good alternative with appropriate pharmacokinetic outcome. Therefore, the validated levodopa HPLC analysis method at low UV wavelength was efficiently applied in pharmacokinetic study.

Performance analysis of liquid-flow-window with submerged heat exchanger

Liquid-filled glazing with submerged heat exchanger is a kind of building integrated solar thermal collector making full use of the transparent façade surface. This novel glazing is capable of preheating domestic water and reducing heat transmission to the indoor space, thus contributes to energy saving of the hot water system and the air-conditioning system. Dynamic thermal model of the glazing system has been developed by assuming uniform temperature and cellular flow in the window cavity. In this study, CFD analysis was employed to verify the assumed liquid flow pattern and temperature distribution. Then parametric study was carried out to assess the impact of several key influencing factors, including glass material, feed water flow rate, and cavity thickness on the thermal performance. The investigation supported an appropriate cavity thickness of 10 mm and feed water flow rate of 1000 ml/min per m2 glazed surface area for effective thermal performance. The use of two absorptive glass panes in the double-glazing gives the best thermal efficiency and electricity saving. The thermal performance of this new design was also compared with the buoyant-flow window design based on typical summer and winter conditions of Hong Kong. The results indicate its superiority and significance in green building development.

Zero-crossing temperature of ultra-stable optical reference cavity measured by optical transition spectrum

In an experimental system of <sup>87</sup>Sr atomic optical lattice clock, the free-running 698 nm diode laser is locked in an ultra-stable optical reference cavity to obtain the ultra-stable narrow linewidth laser with good short-term frequency stability. The ultra-stable optical reference cavity, which is usually composed of glass material doped with titanium dioxide for ultra-low thermal expansion coefficient and two highly reflective fused quartz mirrors, is called ULE cavity. The cavity length is prone to being affected by mechanical vibration, temperature change, airflow, etc. The stability of the cavity length determines the stability of the final laser frequency. Near the room temperature, there exists a special temperature point for the ultra-low expansion glass material, at which temperature its thermal expansion coefficient becomes zero, which is called the zero-crossing temperature. At the zero-crossing temperature, the length of the ULE cavity is not sensitive to the temperature fluctuation, reaching a minimum value, and the laser locked to the ULE cavity has a minimum frequency drift. In order to reduce the influence of temperature on the laser frequency instability, the zero-crossing temperature of the ultra-stable optical reference cavity of 698 nm ultra-stable narrow linewidth laser system is measured by using the clock transition spectrum of the strontium atomic optical lattice clock. The frequency drift and frequency instability of the 698 nm ultra-stable narrow linewidth laser system at zero-crossing temperature are measured by using the change of the in-loop locked clock frequency of strontium atomic optical lattice clock. By scanning the atomic clock transition frequencies at different temperatures, the clock transition spectra at different temperatures are obtained. The second order polynomial fitting of the central frequency of the clock transition spectrum with the change curve of temperature is carried out, and the zero-crossing temperature of the 698 nm ultra-stable narrow linewidth laser system ULE cavity is measured to be 30.63 ℃. At the zero-crossing temperature, the 698 nm ultra-stable narrow linewidth laser frequency is used for in-loop locking of <sup>87</sup>Sr atomic optical lattice clock. The linear drift rate of the ULE cavity in the 698 nm ultra-stable narrow linewidth laser system is measured to be 0.15 Hz/s, and the frequency instability of the 698 nm ultra-stable narrow linewidth laser system is 1.6 × 10<sup>–15</sup> at an average time of 3.744 s. The determination of ULE cavity zero-crossing temperature for the 698 nm ultra-stable narrow linewidth laser system is of great significance in helping to not only improve the instability of the laser system, but also increase the instability of <sup>87</sup>Sr optical lattice clock system. In the future, we will improve the temperature control system of the ULE cavity in the 698 nm clock laser system, enhancing the temperature control accuracy of the ULE cavity and reducing the measurement error, thus achieving a more accurate zero-crossing temperature and further improving the frequency instability of the 698 nm ultra-stable narrow linewidth laser system.