Constant Temperature Operation Research Articles

Tailoring Heat and Mass Transfer for Next Generation of PEM Fuel Cells

The distribution of operating parameters inside PEM fuel cells under dynamic operating conditions is non-uniform. Designing operating conditions using constant Pt loading and temperature seems to result in a high number of problems for operation due to non-optimized heat and mass transfer. During operation using humidified reactants, large quantities of liquid water are accumulated inside the cell in porous layers and for this reason, it is very difficult to achieve high current densities without purging the cell which results in large waste of hydrogen fuel. If the reactants are not fully humidified, during operation at constant operating temperature, the ionomer in membrane and catalyst layers is prone to dehydration and starvation. By using a spatially variable temperature profile, i.e. variable temperature flow field, it is possible to achieve a delicate balance between the rate of produced water and water vapor partial pressure in such a manner as to achieve fully humidified conditions along the entire active area of the cell without the necessity for external humidification. This concept was studied using a combination of computational fluid dynamics and experimental research and it was shown that the application of a variable temperature flow field can be achieved using liquid coolant with a sufficiently low flow rate which is gradually heated up during the flow through the cell by utilizing the heat generated by the cell for establishing and maintaining the desired temperature profile. This concept was further improved by using a variable temperature profile in conjunction with a graded catalyst design. An experimental and numerical study was conducted to determine the optimal combination of variable temperature and graded Pt loading in the cathode catalyst which will show the highest performance. By comparing the optimal design with variable temperature and graded catalyst vs. isothermal operation with uniform catalyst loading, it was found that the performance can be dramatically increased. The operating current density at 0.6 V for the optimal case was 260% higher while Pt utilization was 19% lower when compared to the baseline isothermal constant catalyst loading case with notably enhanced current density distribution. To further enhance the performance we have designed and optimized novel flow fields with secondary channels for water removal near the cathode outlet using 3D metal printing and the results have shown that it is possible to achieve higher current densities with this simple flow field modification. Our investigation of the novel flow fields also included biomimetic design where we based our flow field on the design of shark skin, which was manufactured using a high-end milling machine with vibration compensation. This novel design utilizes inertial effects in the diffusion layers due to high flow velocities which is a novelty for PEM fuel cells since the flow velocities are commonly in a laminar regime. Utilization of these different new concepts has shown that it is possible to significantly enhance the performance of PEM fuel cells with combined numerical and experimental efforts and elucidates the direction of the research toward the development of tailored anisotropic heat and mass transfer for the next generation of fuel cells with improved performance and durability.Funding: This work has been supported by the Croatian Science Foundation under the project IP.2020-02-6249. Figure 1

Dynamics of constant temperature anemometers for the Martian Atmosphere

The objective of this paper is to understand the limits on the response time generated by the thermal dynamics of the Martian wind sensor of the MEDA instrument, working under Constant Temperature Operation (CTO). This technology has been flown aboard the Mars Science Laboratory, InSight, and Mars 2020. It will be shown that active control thermal anemometry enables a time response to wind fluctuations faster than the time constants defined by the thermal inertia of the sensor components. It will also be shown that the temperature redistributions on the temperature-uncontrolled parts of the supporting structure impose a limit on the bandwidth of the sensor. We present a model of the MEDA hot film anemometers describing what parameters control their dynamical response, why wind tunnel testing confirmed them to be faster than 1 s, and criteria to select materials that reduce the response time to approach 0.2 s.

Design and Optimization of Accumulator Pack

For an electric scooter, a lithium-ion battery with a Acro Butyl-nitrate (ABS) temperature management system was developed. Without the use of active cooling components like a fan, a blower, or a pump used in air/liquid-cooling systems, passive thermal management systems employing ABS can regulate the temperature excursions and maintain temperature uniformity in Li-ion batteries. Therefore, this new type of thermal management system can provide the benefits of a small, light, and energy-efficient system. The simulation results for a Li-ion battery sub-module with twenty 18650 Li-ion cells encased in ABS and a melting point of 114 to 120 °C are displayed. There are many important advantages to using aluminium fins manufactured from 0.7mm thick aluminium sheet between the battery cells in an accumulator pack. The relevance of them is explained in the following ways: Accumulator packs, particularly those used in high-power applications like scooters, can produce large amount of heat when in use. The performance, longevity, and safety of battery cells are all significantly impacted by heat. Aluminium fins serve as heat sinks and enhance heat dissipation by boosting the amount of heat-transfer surface area. Heat can be effectively transferred from the cells to the fins thanks to the thin aluminium sheet. Temperature Control: Battery cell efficiency and longevity depend on maintaining their temperature within a favorable range. By releasing more heat, aluminium fins assist in controlling the temperature. The fins aid in preventing overheating and preserving a more constant operating temperature by efficiently draining heat from the cells. Thermal Uniformity: The accumulator pack's thermal uniformity is enhanced by the inclusion of aluminium fins between the battery cells. Variations in cell temperature can cause performance imbalances and lower pack efficiency because uneven heat distribution can cause temperature differences among the cells. The fins aid in the even distribution of heat throughout the cells, reducing temperature variations and fostering consistent performance. Reduced Hotspots: Hotspots are small, high-temperature regions inside a battery pack that can hasten degradation and pose safety issues. Aluminium fins aid in heat dissipation, which reduces the development of hotspots. The fins' increased surface area enables more effective heat transport, which lowers the possibility of localized temperature accumulation. Improved Safety: Effective heat dissipation with aluminium fins can aid in accumulator packs' increased safety. Battery cells may experience thermal runaway or other dangerous situations as a result of high temperatures. The risk of thermal incidents is decreased by maintaining lower cell temperatures, improving operational safety in general. It's crucial to remember that parameters like spacing, size, and overall pack should be taken into account while designing and using aluminium fins. Additionally, by lowering the amount of heat that is released into the environment, liquid cooled heatsinks can be utilised to lessen the environmental effect of electronic equipment. The following are some benefits of employing liquid-cooled heatsinks: ● more efficient at cooling than heatsinks that use air cooling ● can be used to enhance the functionality and dependability of electronic equipment ● can be used to lessen how harmful electrical devices are to the environment. The following are some drawbacks of employing liquid-cooled heatsinks: ● more expensive than heatsinks that are air-cooled. ● more difficult to install and keep up ● Tend to leak more frequently. Keywords — CFD, 18650,ABS ,ALUMINUM FINS ,DRIVE CYCLE MODELS,EQUIVALENT CIRCUIT MODEL.

Studying the effects of siloxane poisoning on a SnO2 metal oxide semiconductor gas sensor in temperature cycled operation enabling self-monitoring and self-compensation

Abstract This work studies poisoning by the cyclic siloxane octamethylcyclotetrasiloxane on a commercially available semiconductor gas sensor in TCO (temperature cycled operation). The data is evaluated using the Sauerwald-Baur model and the DSR method (differential surface reduction). The sensitivity towards several gases (volatile organic compounds, hydrogen and carbon monoxide) is evaluated and compared with a sensor in constant temperature operation mode. The physical and chemical processes on the sensitive layer as well as the resulting selectivity towards hydrogen are discussed. A feature is identified that can be derived from the Sauerwald-Baur model (the differential surface oxidation, DSO) and that quantitatively expresses the sensor condition regarding siloxane poisoning. With the help of this feature, a self-compensation of the sensor signal is demonstrated.

Synergistic enhancement of phase change materials through three-dimensional macropore lamellar structured MOF/EG composite for solar energy storage and beyond

The concept of high energy storage density, negligible changes in volume and pressure after phase change, approximately constant operating temperature and non-toxic of solid–liquid phase change energy storage are very appealing properties that makes it a good strategy to store heat. However, leakage and single thermal energy storage function has become a bottleneck for the further advances of long-term thermal stability and multifunctionality. It is reassuring to know that Metal-organic frameworks (MOF)-porous carbon materials can offer a solution to continuity challenge for growing demand for multifunctionality in phase change materials (PCMs). Herein, a phase change material (PCM) composite with good shape stability, thermal conductivity, and photothermal conversion capability was designed. EG in the blended system can effectively prevent the agglomeration of ZIF particles while simultaneously providing a high specific surface area and pore volume for the adsorption of paraffin wax. The as-obtained PCM composite possesses a 3-fold enhancement in thermal conductivity, 95.56% photothermal conversion efficiency, and excellent shape stability. It demonstrates the potential of MOFs-enhanced PCM composites for thermal energy storage and highlight the importance of synergistic or hybridization strategies in the development of advanced materials for sustainable energy applications.

Comparative study on operating strategies of the organic Rankine cycle under transient heat source

An effective operating strategy is crucial to the adaptive operation of the ORC unit driven by the transient heat source. The dynamic model of a small-scale ORC prototype is established and validated by the tested data in this study. Three operating strategies are proposed and compared: the constant vapor superheat operation, constant evaporation temperature operation, and optimal evaporation temperature operation. It is found that PI controllers can satisfy the control of the ORC system with evaporation temperature controlled at ±1 °C and vapor superheat at ± 3 °C. The expander output power varies more significantly than the system thermal and exergy efficiencies under heat source fluctuation. The constant evaporation operation is sensitive to the transient heat source and is only recommended for the expander with a strict constraint on vapor temperature and pressure. The optimal evaporation temperature operation is recommended as it has the highest system performance and enables the ORC unit to be adaptive to the transient heat source. The constant vapor superheat mode can achieve close-to-optimal performance by carefully setting the rotating speed of the expander. Thus, it can also be preferred considering its performance, simplicity, and the unique advantage of power supply with a stable frequency.

Shape-stabilized 1-hexadecanol/g-C3N4/Cu composite phase change material with high thermal conductivity for efficient photo-thermal conversion

Phase change materials (PCM) have received much attention for thermal energy storage and release in the form of latent heat. 1-hexadecanol (HD), as a representative of organic phase change materials, has the advantages of high thermal storage density, almost constant operating temperature and stable thermochemical properties, which shows outstanding potential in the field of phase change energy storage. Nevertheless, single HD as thermal storage material inevitably faces challenges in terms of liquid phase leakage, low thermal conductivity, and poor photo-thermal conversion. To further improve the practical application of HD, we demonstrate a convenient encapsulation and modification strategy of composite phase change materials (CPCMs) with low liquid leakage and high thermal conductivity. Hence, a novel shape-stabilized Cu-doped HD/ graphitic carbon nitride (g-C3N4) CPCM was developed for efficient photo-thermal storage. By the melt blending method, HD is infiltrated into tightly stacked and aligned nano-porous g-C3N4, and the carbon-based lattice inlay achieves the encapsulation of HD to solve the leakage problem during the solid–liquid phase transition. Then, metallic Cu powder is introduced to further strengthen the thermal conductivity of the materials. With this encapsulation and modification strategy, the obtained 5 wt% Cu-doped HD/g-C3N4 composites (CPCM3) exhibits superior performance in both thermal and optical energy storage. This composite has appropriate phase change temperature and extremely high heat storage density, with melting temperature and latent heat of 48.88 °C and 249.63 J/g. The corresponding solidification temperature and latent heat is 48.52 °C and 242.22 J/g, respectively. Its thermal conductivity is enhanced to 0.5307 W/m·K, which is 59.8% higher than pure HD. The photo-thermal conversion efficiency is up to 81.6% for rapid solar energy harvesting and delivery. In particular, after 100 times thermal cycling tests and thermogravimetric analysis, this special CPCM can maintain good thermal reliability and thermal stability. In conclusion, the composite phase change materials obtained by the synergistic modification strategy of nano-porous g-C3N4 and metallic Cu significantly improved the thermochemical properties of HD. This work provides a practical and efficient synthetic strategy for the preparation of CPCMs, which is expected to present a promising future in the field of solar conversion and storage.

Recent Breakthroughs and Improvements in Phase Change Material Melting in a Triple-Tube Thermal Storage Unit

PCMs have a huge storage capacity, improved heat transfer capability, and a constant operating temperature. PCMs have a weak conduction heat transfer coefficient, which slows melting and reduces energy storage. To increase thermal energy storage system efficiency, performance augmentation technologies are being developed. These strategies include using fins, metal foams in PCMs, and high-thermal-conductivity nanoparticles. This article presents a complete overview of experimental, numerical, and experimental and numerical investigations on melting enhancement of phase change material in triplex-tube thermal energy storage. Fins, nanoparticles, and both are used. This article reviews works on melting enhancement of phase transition material in triplex-tube thermal energy storage. In addition, recent findings and research developments will be summarized. This article covers setting up, examining settings, and discovering results.

Sensitivity of thermal conductivity vacuum gauges for constant current and constant temperature operation

To optimize the measurement range of thermal conductivity vacuum gauges, an expression for the sensitivity is required that takes into account all geometrical, material-specific, and operating parameters. Therefore, equations of the sensor output signal as a function of the pressure for the constant current and the constant temperature mode have been developed analytically. Based on these equations, the sensitivity of the vacuum gauge and its influencing parameters was investigated and discussed. For comparable conditions, the constant temperature operation shows a significantly higher sensitivity for high pressures, while the constant current operation shows higher sensitivity at low pressures. The sensitivity in both the constant current and the constant temperature mode depends on the ratio of the filament surface area and the parasitic thermal conductance. In addition, for the constant current operation, the sensitivity also depends on the current value and the temperature coefficient of the filament resistor. For the constant temperature operation, the sensitivity additionally depends on the distance of the filament and the reference plane. However, to extend the measurement range of a thermal conductivity vacuum gauge toward low pressures, a reduction of the parasitic thermal conductance is mandatory for both the constant current and the constant temperature mode.

Minimizing entransy dissipation for heat transfer processes withq∝Δ(Tn)and heat leakage

Heat transfer process with heat leakage and generalized radiative heat transfer law (HTL) [q∝Δ(Tn)] is investigated. Optimality condition for the minimum entransy dissipation (MED) is derived by applying average optimal control theory. On the basis of the general optimization result, the results for four special cases of Newtonian [q∝Δ(T)], linear phenomenological [q∝Δ(T−1)], radiative [q∝Δ(T4)], and mixed [q∝Δ(T4) with q∝Δ(T)] HTLs are further obtained. Optimal paths are compared with the common strategies of constant heat flux rate and constant hot fluid temperature operation. Numerical examples are presented, and influences of heat transferred amount and heat leakage on optimization performances are analyzed.

Encapsulation of inorganic phase change thermal storage materials and its effect on thermophysical properties: A review

Latent heat energy storage has received lots of concern on account of its high energy storage density and almost constant operating temperature. Phase change materials (PCM) possess unavoidable defects, like flammability, low thermal conductivity, subcooling, phase separation, etc. Encapsulation techniques have been adopted to address these challenges. Many efforts have been devoted to this by researchers, but the bulk of the work is based on organic PCMs, and particularly, reviews on encapsulating organic PCMs are frequent. In contrast, there are only a handful of comprehensive reviews on encapsulating inorganic PCMs, which hardly deliver complete information. Therefore, this review aims to provide a comprehensive look at the recent research advances for encapsulated inorganic PCMs. Two broadly adopted encapsulation methods are observed: core-shell encapsulated PCM and shape-stabilized PCM. Three main preparation processes for core-shell encapsulation (in situ polymerization, solvent evaporation and sol-gel methods) are described. The two former techniques are mostly adopted for the microencapsulated hydrated salt PCMs and forming organic shells. The latter is suitable for inorganic shells. The porous skeleton materials widely adopted for shape-stabilized PCMs are presented. The advantages and disadvantages of porous carbon, porous clay minerals, porous silica, and other materials were evaluated. In addition, thermophysical properties, such as supercooling, phase separation, phase change temperature, tent heat, thermal conductivity and thermal cycling reliability are discussed. It was found that encapsulation technology can have positive effects on thermophysical properties. It is hoped that this work will assist readers in gaining a comprehensive insight into the development of inorganic PCMs.

Multi-regional building energy efficiency intelligent regulation strategy based on multi-objective optimization and model predictive control

With the improvement of occupants’ requirements for quality of life, the functions and regions of buildings are becoming more and more refined. Large-scale buildings with multi-regional function come out increasingly. The traditional uniform constant temperature design and operation management technology can no longer meet the needs of occupants, as the dynamic thermal comfort level of human body in different regions has great discrepancy. This paper conducts the whole chain regulation model for large multi-regional buildings from demand level, application level and control level. Aiming to reduce the load reasonably on the premise of thermal comfort, a model of dynamically adjusting the set point temperature in different regions is established on demand level. As load demand refers to the energy provided by the operation of HVAC system, the controlled parameters values are obtained by adopting the intelligent optimization strategy for the application level. On the bottom control level, the optimized parameters are managed by model predictive control (MPC), which has great advantage of rapid response. It is found that the strategy of dynamically adjusting the temperature set point in typical day can reduce the load demand by 6.16% without sacrificing the comfort of indoor personnel. Based on the load demand optimization, the operation optimization and MPC strategy is further adopted for application and control level by simulation, and can realize the total energy saving of HVAC system by 12.78%.

Transparent hydrophobic, self-cleaning, anti-icing and anti-dust nano-structured silica based thin film on cover glass solar cell

Silica thin film with anti-reflective, hydrophobic and anti-icing properties was prepared on glass substrate by a sol-gel method. For this purpose, silica sol based on the TEOS and TMMS precursors were prepared. Then, different TCMS concentrations were added to the primary sol solution. Film deposition on glass substrate was performed by a dip coating method. Hydrophobicity, transparency, morphology and chemical analysis of the films were investigated. Icing tests were performed at a constant operating temperature of -12 °C. Also, the self-cleaning behavior of the samples was evaluated by iron oxide powders. The thin film stability under ultraviolet light irradiation was investigated. The results showed that with increasing TCMS, the transmittance of the glass coated substrate increased until 0.2 ml and then decreased. Also, the results of the water contact angle measurements showed that the contact angle increased with increasing the TCMS concentration until 0.33 ml (123°) and then with more increasing the TCMS concentration, it remained constant. Icing tests showed that the start time of the icing and the time required for complete icing on the thin layer of modified silica base with 0.2 mm TCMS is much longer than the uncoated glass. Also, the self-cleaning test showed that the glass coated sample has a self-cleaning behavior. After exposure to the ultraviolet light, the hydrophobicity and transparency of the glass coated sample did not disappear.

Economic dispatch for a regionally integrated heat and electricity system with variable pipeline flow direction

Traditional models of heating networks are not able to take into account the changes in the value and the direction of pipeline mass flow in a multi-heat-source district heating network or the time delay characteristics of the network with constant temperature and variable flow operation. A day-ahead dispatch model for regional integrated heating and electricity system based on improved second-order cone programming method is therefore proposed. We first construct a heating network transmission model with variable value and direction of pipeline mass flow, and then use a convex relaxation to transform this nonlinear model into a mixed-integer second-order cone programming model. A hydraulic time-delay correction model is then constructed to reflect the dynamic characteristics of the heating network under variable mass flow conditions. Finally, we establish a model of an electric boiler with thermal storage to improve the flexibility of the distribution network. Case studies are used to show that the optimised results are more economical in terms of both the variable value and direction of mass flow. The proposed programming method retains the variability in the flow direction and achieves precise relaxation without the need to solve for the initial value. We also verify that the hydraulic time delay characteristics have a strong influence on the optimised results of the regionally integrated heat–electricity system under conditions of constant temperature and variable flow. In addition, an electric boiler with thermal storage can reduce renewable energy curtailment and effectively improve operational flexibility.

Relative Stress Analysis of Gas Turbine Blade for Various Alloying Materials

Gas turbines provide a reliable and efficient production of power in both pilot power plants and aircraft propulsion. The operating cost of the modern gas turbines is greatly influenced by the durability of hot section components. To cope up with the increasing temperature, there has been an evolution of new generation blade materials. At elevated temperature conditions, thermal stress and resulting deformations can affect the power developed and efficiency. In this paper a finite element simulation has been made on a fixed blade profile to explore various factors affecting the turbine blade. Variety of existing and new generation materials have been considered a under a boundary condition of constant high pressure and high Operating temperature was varied between 1000°C-1400°C. The development of stress and deformation along with the heat flux have been studied for finding the most effective manufacturing alloy for gas turbines.

Hybrid thermal performance enhancement of shell and tube latent heat thermal energy storage using nano-additives and metal foam

Phase change materials (PCMs) are popular for effectively storing thermal energy due to their high thermal energy density and nearly constant operating temperature. However, a restriction for their effective application comes up due to their poor thermal conductivity. The main aim of this numerical investigation is to analyze the potential of two heat transfer augmentation methods, (i.e., metal foam and nano-additives) for a shell and tube. A mathematical formulation considering the extensions of Brinkman and Forchheimer made on the model of Darcy for porous media is validated with experimental data available in literature and used for simulations. The model is used via a commercial CFD code for simulations of heat transfer and phase change evolution during both charging and discharging processes in the heat exchanger. The thermal performance of the heat exchanger is examined through liquid fraction evolution, time for complete cycle and stored energy. The effects of operational and structural parameters including inlet temperature, metal foam material, foam porosity (0.95 and 0.98), pore density (10, 40, and 70 ppi), and nanoparticle volume fraction (0, 1 and 3 vol%) are investigated. Results show that the metal foam material and nanoparticle concentration have a significant effect on the thermal performance of PCM in shell and tube. Metal foam and graphene nanoplatelets reduce the charging and discharging times by up to 96.11% and 96.23%, respectively. Furthermore, lower porosity foam expedites the charging/discharging process whereas the pore density has no noticeable effect. The findings of this study are hoped to be helpful for designing efficient thermal energy storage units.

Performance enhancement of latent heat storage systems by using extended surfaces and porous materials: A state-of-the-art review

Latent heat thermal energy storage (LHTES) is a widely accepted technology because of its high energy density at nearly constant operating temperature. The main disadvantage of LHTES is the low thermal conductivity of the storage material, which affects the charging and discharging rates. Therefore, various methods have been used for enhancement of thermal performance of phase change materials in LHTES including utilizing fins and porous materials with high thermal conductivity. These two main methods are intensively addressed in the literature. In this paper, these techniques are reviewed and discussed by classifying them regarding their prominent specifications. First, the enhancement by extended surfaces is reviewed focusing on the fin geometries. Secondly, metal foams are investigated with respect to the materials they are made of and their structure such as gradient or partial porosity since these techniques are promising methods for significant performance augmentations. Thereafter, in the following section, the combination of these two techniques, which can be called a hybrid technique, is examined and recent research works are reviewed. The literature review showed that innovative fin shapes are increasingly investigated by numerical simulations. However, there is a significant need for experimental validations. On the other hand, metal foams exhibit remarkable thermal performance, nevertheless, their utilization is not as prominent as fins since utilization of fins is a simpler and cost-effective method. Combining these two methods is recently getting increasing attention as it can further improve thermal performance of PCMs. After reviewing the relevant recent studies, conclusions drawn from the present literature study are outlined. Additionally, some directions and recommendations for future research are highlighted at the end of the paper.

Performance Analysis of Fuzzy Logic Controller Applied on Portable Roaster

Roaster is a device commonly used to roast various products, especially for food processing. In the roasting process, temperature parameter plays a major role in determining the final quality of the roasted product. In real-world applications, some products must be roasted at low temperatures such as cocoa products and others must be roasted at high temperatures such as coffee products. In addition, roasting is sometimes not always carried out at a constant temperature, but sometimes it must be done at various roasting temperature levels for the purpose of forming the optimal flavour. Thus, a roaster must be able to operate at the desired operating temperature, not only a constant operating temperature but also able to work with varying operating temperatures. For this purpose, a roaster must be equipped with a reliable temperature controller. Several control models have been developed by many researchers, including fuzzy logic control. This research was conducted to design, implement, and evaluate the performance of a control system based on fuzzy logic on a laboratory scale portable roaster. For this study, a fuzzy control system with two input variables, namely the difference in temperature and changes in temperature difference as well as one control signal output variable, had been designed to regulate the roasting temperature on the roaster. To evaluate its performance, the domain membership function of the input and output variables was varied. The design was then applied to the microcontroller-based control system hardware attached to the portable roaster. The test results show that the fuzzy logic control was able to regulate the roast temperature stably. With a varied roast temperature setpoint, the control system can follow and maintain the target with small temperature variation.

Methods of increasing the reliability of turbine elements

The purpose of the work. Statistical and experimental analysis of coating methods on the turbine nozzle apparatus to increase the temperature regime.
 Research methods. Calculation method of finite elements, experimental.
 The results obtained. Studies have shown that the use of thermally protective coatings TZP thickness of 250 мm with a thermal conductivity of 1 W / mK on the two steps of the turbine can implement one of two possibilities:
 - at constant operating temperature of the blade material to increase the temperature of the gas in front of the turbine by about 100 °C, which will increase efficiency and fuel savings by more than 13 %;- without changing the temperature of the gas in front of the turbine - to increase the durability of the blades by about 4 times, due to a decrease in their operating temperature. The analysis of two methods of drawing TZP was carried out, in the work the estimation of a temperature condition of the nozzle device (CA) of the turbine of a high pressure of the engine, decrease in its temperature due to drawing TZP and increase of its resource is carried out. The problem was solved by applying TZP on the blades of the nozzle apparatus. The analysis of two methods of drawing TZP was carried out, the estimation of a temperature condition of the nozzle device (CA) of the turbine of high pressure of the engine, decrease in its temperature due to drawing TZP and increase of its resource is carried out.
 Scientific novelty. The problem of creating efficient, economical and reliable gas turbines is the most difficult among the many problems that arise in the development of gas turbine construction. Important elements of turbines are working and nozzle blades, the material and design of which determine the allowable gas temperature in front of the turbine and thus directly affect the technical and economic performance of the gas turbine engine.
 Practical value. The obtained results are important for the further development of aircraft engine construction, due to the application of TZP achieved an increase in the resource of CA from 40,000 hours to 67,000 hours.

Latent heat energy storage system using phase change materials and techniques for their performance improvement: A Review

Entire world is struggling to explore newer methods to overcome the energy crisis. With limited and exhausting energy resources researchers around the world are finding efficient ways to store thermal energy. One of the efficient ways is to store thermal energy in the form of latent heat energy using phase change materials (PCMs). Latent heat storage (LHS) units have been widely adopted owing to superior energy storage density and constant operating temperature. But the thermal performance of these systems is limited due to low thermal conductivity of the PCMs. Researchers across the globe working on approaches to improve the thermal performance of these systems. The present review paper is concerned with a review on PCMs, methods to improve performance of LHS system using PCMs with special emphasis on use of various additives such as nano particles and porous materials to increase the thermal performance of PCMs and types of PCMs for specific applications. The factual data presented in this paper would be helpful in selection of appropriate PCM for specific application, and to adopt suitable performance enhancement technique to obtain most optimal LHS system