Optimized Car Cooling System Using Solar Energy

We studied the application of the fiber Bragg grating (FBG) temperature sensing method based on support vector regression optimized by a genetic algorithm (GA-SVR) for constant and decreasing external ambient temperature cases by simulation. The external ambient temperature could be retrieved from both the transient FBG wavelength and its corresponding change rate using GA-SVR, before the FBG temperature sensor reached the thermal equilibrium state with the external ambient temperature. FBG wavelengths and their corresponding change rates in the cases of FBG sensor temperatures higher and lower than the external ambient temperature were studied and used to construct the training data set. We found that there exist singularity points in the curves of the wavelength change rate when the FBG sensor temperature is higher than the external ambient temperature in some cases, which is different from the case where the FBG sensor temperature is lower than the external ambient temperature. Its application for sensing the constant and decreasing external ambient temperature in real time was demonstrated with an accuracy of 0.32°C in those two cases. It also indicates that for real applications of this temperature sensing method where the external ambient temperature varies randomly, the FBG sensor temperature changes rather than the external ambient temperature changes play the dominant role. What is more, the demodulation time was decreased to 0.002s, which is approximately 0.05‱ of the time constant of the FBG temperature sensor. In other words, this method makes it possible to realize the external ambient temperature determination using a time smaller than the time constant of the FBG sensor. The high sensing accuracy and fast demodulation speed are crucial for future high-performance real-time FBG temperature sensing.

본 연구의 목적은 Display 산업의 중요성에 주목하여 옥외 광고를 위한 LCD 패널용 콘솔(이하 'LCD 콘솔'이라 한다.)을 개발하는데 있다. 본 연구의 핵심 과제는 LCD 콘솔의 내부온도를 제어할 수 있도록 해주는 냉각시스템(Cooling System)을 개발하는 것이다. 냉각시스템은 상용화되어 있는 냉각휀(Cooling Fan), 히트싱크(Heat sinks), 열전소자(Thermo Electronic Module) 등의 제품들을 시스템적으로 통합시키는 응용기술로서 통계적 검정기법을 적용하여 개발되었다. 본 연구는 먼저 냉각시스템을 설계/제작한 후 실험을 통하여 냉각시스템 제어에 필요한 인자들의 설정 값들을 구하는 과정을 보였다. 이어서 개발된 냉각시스템을 이용하여 46인치 LCD Panel이 탑재된 LCD 콘솔을 설계/제작하고 실험을 통하여 완성품 LCD 콘솔의 성능을 확인하는 과정을 보였다. The development of the console for exterior advertizing LCD Panel(LCD Console) is the purpose of this study with regard to importance of display industry. In this study, the most important point is to develop the cooling system for LCD Console. It is developed by using systematic application techniques and statistical tests and analysis to integrate commercial components, cooling fan, heat sink, thermo electronic modules etc, of it. This study, at first, shows design/manufacturing process of the cooling system and the setting process of control factors to control through experimentation. Next, after constructing the complete console, 46 inch LCD Panel and the cooling system are built in, the performance test of it is shown through experimentation.

Investigating photovoltaic module performance using aluminium heat sink and forced cold-air circulation method in tropical climate conditions

The present work evaluates thermal exchange through a double-layered mini-channel heat sink used as a cooling system for electronic components. Different factors influencing heat exchange enhancement were investigated using ANSYS-Fluent<sup>©</sup> software, which enables the simulation of the fluid flow and heat transfer. The evaluation of thermal exchange between the cold fluid and heated solid with high thermal dissipation has been accurately analyzed under the effect of system geometry, fluid nature, and cooling system material. The numerical outcomes demonstrated that the heat transfer quality significantly increases with the variation of the system shape, where the cooling system presented a significant reduction of average temperature by around 62%-65%. In addition, using pure water as the system coolant improved the heat transfer rate by about 42%-47% for different Reynolds number values by comparing it with ethylene glycol. Concerning the cooling system materials, the selection of the materials depends on the analysis of their thermal properties with the evolution of temperature and thermal exchange. Therefore, using copper as a cooling material improves the overall performance of a cooling system, delivering higher efficiency and performance.

The objective of the present investigation is to perform a feasibility study of the working of a passive cooling device employing ferrofluid as a cooling medium and designing its heat sink. A computational study has been performed using COMSOL MultiPhysics, wherein a feasibility study was first done to check the working of a ferrofluid-based cooling device, and thereafter a design strategy was developed for selecting the number and height of annular fins for cooling of the ferrofluid in the closed channel. Ferrofluid was allowed to flow in the miniature cooling system in the presence of an external magnetic field produced by a permanent magnet. As ferrofluid flows through the loop, the thermal energy it absorbs should be dissipated so that colder ferrofluid is available for the next cycle of operation. Annular fins have been employed in the heat sink region to augment the heat dissipation rate. The effect of fin height and spacing on temperature drop across the heat sink has been studied, and it was found that the number of fins has a direct relation with the temperature drop across the heat sink. Fin height also contributes to the temperature drop, but, beyond a certain value, its effect was found to be insignificant.

Ambient temperature has an profound effect in the physiology of all animals and accurate evaluation of both external and internal temperatures is therefore an essential factor for fitness and survival. To this end, animals possess specialized cells and organs, which have evolved to obtain accurate information about this crucial factor. Drosophila melanogaster relies on different thermosenstive neurons to gauge both its internal as well as the external temperature. One thermosensitive organ is located in the arista, a feather like structure protruding from the third segment of the fly’s antenna. It has been found that the arista houses six neurons, three of which exhibit excitatory responses to heat (and were therefore called hot cells) and three which are responding to cold (named cold cells). In this study, I characterized the responses properties of the thermosensory organ in the arista and I analyzed the role that the TRP ion channel NOMPC, classically associated with mechanosensation, plays in this particular structure. Using Ca2+ imaging, I found that the amplitude of temperature evoked Ca2+ responses appears to be determined by the relative change in temperature, rather than the absolute value. I furthermore found evidence that the TRP channel NOMPC can be found in the hot cell population of arista neurons. Data obtained in this study shows that a knockdown of nompC leads to a reduction in the temperature response amplitude of hot cells. Homozygous nompC null mutants exhibit a stronger reduction in amplitude than heterozygous mutants, hinting at a possible gene dosage effect. The response modulation via NOMPC also affects behaviour, as locomotion experiments in a temperature gradient showed that nompC knockdown mutants show later hot avoidance and have a higher preferred temperature. The effect in both physiological and behavioural experiments could be rescued. Taken together, the findings of this study show that the thermosensitive neurons in the arista of Drosophila function as relative temperature sensors and that NOMPC serves an important modulatory role for the temperature evoked responses of these neurons.

Cooling of Laser Slab by Forced Convection through a Heat Sink

The energy source for electricity generation in Indonesia is mostly supplied from fossil energy, but this energy source will run out in the next 20 years. Various researches are now leading to the development of alternative energy sources such as solar energy. There are two kinds of solar energy utilization technologies, namely solar thermal energy technology and solar photovoltaic energy. Thermal solar energy in Indonesia is generally used for the drying process of agricultural and marine products, while photovoltaic solar energy is used to meet electricity needs, especially in remote areas. Most solar panels are installed permanently at a fixed angle. This causes the solar panels to be unable to absorb solar heat optimally because the sun is always moving. Therefore we need a tool that can move solar panels to follow the direction of the sunlight. The tool used is known as a solar tracker panel. This tool consists of an Arduino Uno as a microcontroller, an LDR (light dependent resistor) as a sensor and a servo motor to drive the solar panels. This tool is double axis, so it can (up and down) as well (to the left and right). The purpose of making this tool is to optimize the absorption of sunlight into the solar panels in order to further reduce the cost of spending electricity PLN. This type of research used in this research is quantitative research with a descriptive approach. The test results proved to be more efficient than the patented on-site solar panels. This tool is applied as a source of energy for water pumps and also for other items such as lamps,.etc

Battery temperature is one of the most important states to monitor to ensure good operation and safety, it has a significant impact on cell performance and life. Sensors embedded internally provide more accurate measurements of battery temperature and can therefore support more advanced battery characterisation. [1] Previously temperature sensors have been embedded within the centre of cells without considering how sensor location and cell orientation could impact the accuracy of the measurement. [1] In this work we investigate: (i) the in plane temperature change both inside and on the external surface of the cell, (ii) the difference in temperature change between internal and corresponding external sensor (cross plane temperature change) and how they vary in different cell orientations.We integrate bespoke non-invasive 10kOhm thermistor arrays (0201 size) internally (see figure 1f), on top of the electrode stack of A7 Li-ion pouch cells (1Ah NMC622/graphite), manufactured within the university. In addition, an external thermistor array is mounted on the pouch bag, the seven sensors on both arrays are aligned for direct comparison. An external thermocouple is also used as a reference. The experiment is undertaken in a thermal chamber (representative of a typical chamber used in literature), left to stabilise to 25oC for two hours before proceeding with the experiment. The thermal chamber comprises a volume of 0.27m3 with heat circulation fans located towards the top of the chamber, in principle, ensuring homogeneous temperature during testing. The temperature change is monitored throughout the test profile shown in figure 1a & b, a current magnitude of 2C is applied for a duration of 10 seconds at state of charge levels of 100 %, 80 %, 50 % and 20%.Four different cell configurations (A-D) are considered, see figure 1c. Configuration A represents the use case when the internal thermistor array is placed towards the side facing upwards and the external array is mounted on the surface facing downwards. The thermocouple in this configuration is on the topside, in all configurations it is placed centrally. Configuration B represents when the external thermistor array is moved to the top surface of the cell, here the pouch bag material only separates the two arrays. In configuration C the cell is wrapped in an insulating layer and is then reorientated in configuration D.Results from (i) show the same trend throughout all configurations, sensors closest to the electrical tabs experienced the smallest temperature change, similar to results found in [2], whereas the sensors centrally towards the opposite side of the tabs read ~0.45 oC higher, during the 1C discharge of the test program (all temperature change values are extracted from this step). When investigating (ii) we observe the greatest temperature change difference towards the centre of the cell for all cell configurations, where the internal sensors read ~ 0.4oC higher. The temperature change values therefore vary more in plane (i) than cross plane (ii), a similar trend is observed in [3]. The average internal temperature change observed between different cell configurations varied more compared to its equivalent external temperature change, the greatest difference being between configuration C and D and is therefore shown in figure 1d & e. We have shown that at this scale, the cell orientation has a significant impact on the readings than whether the sensor is integrated internally or externally on the cell. If this experiment was repeated on a larger battery the significance of cell orientation on temperature change would further increase. Researchers must be aware of the importance of consistent positioning of the cell and the sensor in the thermal chamber during testing and insulating the cell from the circulation fans.Instrumenting the cell had minimal effects on its life and performance as no capacity and internal resistance differences are present between equivalent cells with no internal sensor. Further work includes integrating the array between the electrode layers to understand how significantly the internal temperature will vary and quantify the reliability between the outer embedded sensors.[1] L. H. J. Raijmakers, D. L. Danilov, R. A. Eichel, and P. H. L. Notten, “A review on various temperature-indication methods for Li-ion batteries,” Apr. 15, 2019, Elsevier Ltd. doi: 10.1016/j.apenergy.2019.02.078.[2] S. Novais et al., “Internal and external temperature monitoring of a li-ion battery with fiber bragg grating sensors,” Sensors (Switzerland), vol. 16, no. 9, Sep. 2016, doi: 10.3390/s16091394.[3] T. Waldmann et al., “Influence of Cell Design on Temperatures and Temperature Gradients in Lithium-Ion Cells: An In Operando Study,” J Electrochem Soc, vol. 162, no. 6, pp. A921–A927, 2015, doi: 10.1149/2.0561506jes. Figure 1

Interactions between gravity waves and cold air outflows in a stably stratified uniform flow forced by various combinations of prescribed heat sinks and sources are studied using a hydrostatic two-dimensional nonlinear numerical model. It is found that the formation time for the development of a stagnation point or reversed flow at the surface is not always directly proportional to the Froude number when wave reflections exist from upper levels. It is shown that a density current is able to form by the wave-outflow interaction, even though the Froude number is greater than a critical value. This is the result of the wave-outflow interaction shifting the flow response to a different location in the characteristic parameter space. A density current is able to form or be destroyed due to the wave-outflow interaction between a traveling gravity wave and a cold air outflow. This is proved by performing experiments with a steady-state heat sink and an additional transient heat source. In a quiescent fluid, a region of cold air, convergence, and upward motion is formed after the collision between two outflows produced by two prescribed heat sinks. After the collision, the individual cold air outflows lose their own identity and merge into a single, stationary, cold air outflow region. Gravity waves tend to suppress this new stationary cold air outflow after the collision. The region of upward motion associated with the collision is confined to a very shallow layer. In a moving airstream, a density current produced by a heat sink may be suppressed or enhanced nonlinearly by an adjacent heat sink due to the wave-outflow interaction.

To evaluate the effects of age and season on menstrual cycle length and basal body temperature (BBT). We also examined the effects of climate on cycle length and BBT, taking into account Japanese geographic and social characteristics. In this retrospective cohort study, we analyzed data from 6 million menstrual cycles entered into a smartphone application from 310,000 females from 2016 to 2017. Only those who entered more than 10 cycles in 2 years were included. Generalized estimation equations were used to adjust for confounding factors and for within-person correlations of multiple records. Multiple regression analysis was conducted, with age, external average temperature, precipitation amount, and sunshine hours as confounding factors. The mean menstrual cycle length increased from age 15-23 years, subsequently decreased up to age 45 years, and then increased again. Average follicular phase body temperature showed no significant age-dependent changes, but luteal phase body temperature gradually increased up to 29 years and then stabilized and started to decrease after age 42 years. A significant association between external temperature and body temperature (follicular and luteal phase) was observed, though menstrual cycle length did not show such an association. These results, derived from data self-entered into a smartphone application, revealed underrecognized age-dependent and seasonal changes in menstrual cycle length and BBT, which will contribute to a better understanding of female reproductive health in the modern world.

Air cooling systems are currently the most popular and least expensive solutions to maintain a safe temperature in electronic devices. Heat sinks have been widely used in this area, allowing for an increase in the effective heat transfer surface area. The main objective of this study was to optimise the shape of the heat sink geometric model using the Adjoint Solver technique. The optimised shape in the context of minimal temperature value behind the heat sink is proposed. The effect of radiation and trapezoidal fin shape on the maximum temperature in the cooling system is also investigated. Simulation studies were performed in Ansys Fluent software using the Reynolds—averaged Navier–Stokes technique. As a result of the simulation, it turned out that not taking into account the radiation leads to an overestimation of temperatures in the system—even by 14 ∘C. It was found that as the angle and height of the fins increases, the temperature value behind the heat sink decreases and the heat source temperature increases. The best design in the context of minimal temperature value behind the heat sink from all analysed cases is obtained for heat sink with deformed fins according to iteration 14. The temperature reduction behind the heat sink by as much as 25 ∘C, with minor changes in heat source temperature, has been achieved.

A dynamic mathematical model used to predict the performance of passive cooling system by evapo-reflective roof in buildings for hot arid climates has been developed. The cooling system consists of a roof composed of concrete ceiling and flat aluminium plate, separated with air space partially filled with rocks and small quantity of water. Low emissive aluminium sheet with white painting on the upper surface, reduces the heat transfer by radiation during the daytime, an external treatment of the roof used to provide mass transfer to the outside (water vapour). At night, the temperature of the aluminium sheet falls below the temperature of the rocks water upper surface. Water vapour inside the roof condensates and falls by gravity. This heat pipe effect carries heat outwards. Heat exchange is improved by radiation between two humid internal surfaces. The efficiency of this cooling system is studied using finite differences method. Numerical calculations performed for different external temperatures and solar radiation show that the cooling produced by such system is significant. As a result of this, the mean air temperature in the room may be kept a few degrees over the minimum outdoor temperature throughout the day. Allowing natural ventilation of the building in the evening could further, lower the indoor air temperature by 3 to 4°C. The work is continuing.

The design of a thermal management system for an airborne, infrared, optical telescope system is described. This system provides transient thermal management for the optical elements of the system beginning at a high-temperature soak condition of 71°C (159.8°F) on the ground to a low-temperature operating condition of −30°C (−22°F) to −40°C (−40° F) within 45 min after aircraft takeoff. An active cooling system is employed to enable this rapid cooldown. In addition to the low-temperature requirement, the mirrors and lenses must be cooled so that temperature gradients across the optical elements are on the order of 1°C (33.8 °F) to 2°C (35.6 °F). The ambient air available for ground cooling is specified by the military environment to be 55°C (131.0 °F). As the aircraft takes off and climbs to an altitude of 11,582.4 m (38 kft), the ambient air temperature decreases to a low-temperature of −22°C (−7.6 °F) for steady, level flight at at Mach 0.9, this ambient air temperature results in a ram air inlet temperature on the order of 13.5°C (56.3 °F), after the air is captured and diffused to Mach 0.2 prior to entry into a ram air heat exchanger. This ram air heat sink is used to provide a chilled liquid for cooling of optical elements and the turret housing the system. The low temperatures required for this system, which are on the order of −30°C (−22 °F) to −40°C (−40 °F), make the use of forced-convection, liquid-cooling problematic because of the tendancy of liquids to become quite viscous as they approach these low temperature levels. Furthermore, the use of a single-phase heat transfer process will result in temperature gradients within the system. For these reasons, cooling concepts employing single-phase cooling using chilled-liquids have been eliminated from consideration. A low-temperature, low-pressure refrigerant, R-404a, is used as the working fluid. The themal management system uses the optical elements as the evaporator of a two-phase cooling system. The liquid refrigerant is introduced into the optical elements at the saturation temperature and saturation pressure of the liquid. The flow rate of the refrigerant will be controlled in such a manner that all of the heat transfer takes place in the liquid-vapor mixture region of the thermodynamic diagram for R-404a with the refrigerant exiting the elements at an arbitraily determned quality of approximately 0.8. This will assure that all of the heat transfer will be by boiling heat transfer and will take place at a constant temperature and essentially a constant pressure. Since the heat transfer coefficients are large and the process takes place at essentially a constant temperature, the optical elements will be controlled at the saturation temperature of the refrigerant and will be essentially a constant temperature across the expanse of the optical surface. The thermal management system is comprised of an array of TECs configured as a condenser HX. This TEC HX uses ram air as the eventual heat sink and will provide chilled-liquid produced by a liquid-to-ram air HX as the heat sink for the hot side of the TEC array. This system utilizes the system mass as the evaporator and a TEC HX as the condenser in a two-phase heat transfer process to provide rapid cooldown of the system mass to low temperatures in a short period of time and maintain that mass at proper operating temperatures with essentially zero temperature gradients throughout the system.

Most of the reported vortex beam generators generate vortex beams at a fixed frequency, which limits the practical applications. Therefore, it is inevitable to explore a vortex beam generator, which can actively control the operating frequency. We propose a switchable frequency terahertz vortex beam metasurface, it is freely switchable under single-frequency mode and dual-frequency mode by changing the external temperature, the phase state of vanadium dioxide (VO<sub>2</sub>) is also changeable. External temperature changes will cause VO<sub>2</sub> to transform from insulating state to metallic state. Generally, VO<sub>2</sub> conductivity can increase by several orders of magnitude as operating temperature changes. By using the phase change property of VO<sub>2</sub>, we can obtain a metasurface with switchable operating frequencies. For operating at room temperature, the proposed metasurface behaves as a single-frequency terahertz vortex generator. When (left-handed circularly polarized, LCP) terahertz wave is vertically incident on the metasurface, it generates vortex beams with different topological charge numbers at a frequency of 1.1 THz, and the mode purity is above 85%. The simulation results show that the mode purity of the vortex beam with the topological charge <i>l</i> = 1 is 90%, and the mode purity is about 91.1% for the vortex beam with <i>l</i> = 2, and 85.4% for the vortex beam with <i>l</i> = 3. When the external temperature is of 68 ℃, the designed metasurface becomes a dual-frequency vortex beam generator. At this time, the operating frequencies of vortex beams with different topological charges (<i>l</i> = 1, 2, 3) are 0.7 and 1.23 THz, whose mode purities are both above 60%. That is to say, the corresponding mode purities at topological charge with<i> l</i> = 1 for two operating frequencies are 89.1% and 71.6%, respectively. The mode purities are 83.2% and 94.4% with topological charge <i>l</i> = 2, respectively. The mode purities are 62.4% and 68.2% with topological charge<i> l</i> = 3, respectively. Therefore, the proposed switchable frequency terahertz vortex generator provides a new design idea for working frequency modulation in wireless terahertz communication.