Quantity Of Phase Change Material Research Articles

Phase Change Materials (PCM) for a Zero-carbon Food Preservation Technology in Remote Areas

Abstract Phase Change Materials (PCM) are thermal storage materials that are capable of storing renewable energy and improve the performance of a solar cooling system. Since solar power is not consistent everywhere and the operating conditions of cooling systems are varying, a specific study is needed to implement this principle for a particular location. This research work aims at developing small-scale solar domestic refrigerator and freezer systems to work with PCMs and solar energy. The software, System Advisor Model is used to select the PV system for the location. An experimental setup of a 210-litre refrigerator and a 250-litre chest freezer with PCM cladding is used. The quantity of low-temperature PCM was varied, and the energy efficiency of the system, temperature distribution inside the refrigerated space, and on-off cycles of the compressor were studied to ensure its technical feasibility. The results from the study showed that the use of PCM could run the system during non-sunshine hours with an 8-15% reduction in energy consumption. The pulldown time was promising, and the off-cycle time of the compressor was long, which ensures that the system can work at the desired temperature during the off-sunshine hours. The temperature distribution inside the freezer and food compartments of the refrigerator for various quantities of PCM was found to be from -14 to -16°C and from 1 to 8°C, respectively. Moreover, the calculated total equivalent warming impact was 15-60% lower than the conventional system. A detailed study on the economic benefits and risk analysis can be conducted to mature the technology

Numerical investigation of melting process enhancement in shell and coil latent heat storage tanks by the simultaneous use of conical coil and conical shell

Efficient energy storage rates are crucial for latent heat energy storage units. Building on previous studies highlighting the benefits of shell and helical tube configurations, which enhance energy storage rates through increased heat exchange areas, this research introduces a novel configuration featuring a combination of conical shell and conical coil. Various geometric variations, including conical/cylindrical shells and conical coils, are explored to assess their impact on charging performance using numerical simulations based on the enthalpy-porosity method. The study investigates three different numbers of coil turns (4, 6, and 8) for each configuration. Results demonstrate that the proposed conical shell and conical coil configuration significantly accelerates the melting rate, achieving a liquid fraction of 0.897 within 160 min—an improvement of 7.6 % compared to the conventional shell and helical tube configuration with the same phase change material quantity. Additionally, increasing coil turns from 6 to 8 yields an 8.8 % rise in the liquid fraction for the simple cylindrical case, comparable to the 7.6 % increase achieved by the proposed conical configuration. The findings underscore the preference for geometry modifications over increasing coil turns, as the latter leads to greater space occupation within the tank, resulting in reduced energy storage capacity and a concomitant 30 % undesirable increase in heat transfer fluid pressure drop.

Development of artificial leak-free phase change material (PCM) aggregates using emulsion technique, cementless binder, and cold-bonded pelletization

The present study developed new leak-free artificial PCM aggregates using an emulsion technique, cementless binder, and cold-bonded pelletization (hereafter, PCM-surfactant-aggregate) and significantly increased the PCM quantity in aggregates without PCM leakage, which was demonstrated from differential scanning calorimetric (DSC) and thermogravimetry (TG) results. The PCM-water-emulsion was produced by using a non-ionic surfactant, Pluronic P123, and used as mixing water to produce cementless artificial aggregates using Ca(OH)2-Na2CO3-activated fly ash and cold-bonded pelletization. The produced artificial PCM-surfactant-aggregates showed no material separation during preparation and no visual PCM leakage on the surface and were lightweight aggregates in terms of compressive strength (ASTM C330). In the concrete testing results, the 28-day compressive strength was 18.1 MPa when all fine and coarse aggregates were replaced with artificial PCM-surfactant-aggregates and the thermal conductivity decreased with increasing aggregate content. The testing on the heated concrete specimens having PCM-surfactant-aggregates indicated no PCM leakage, no dimensional change, and no strength reduction due to the PCM phase transition from solid to liquid. Overall, the concrete containing PCM-surfactant-aggregates showed an increase in the lowest temperature and a decrease in the highest temperature in the temperature profile of the indoor space in the dynamic heat flow test.

Simulation study of drilling fluid cooling in long horizontal wells based on phase change heat absorption

ABSTRACT The shale gas resources found in deep formations are abundant and represent a crucial area for current and future shale gas development. However, as shale gas exploration and development intensify in China, an increasing number of high-temperature formations are being encountered during drilling, presenting significant challenges to drilling engineering and severely constraining the development of deep shale gas exploration. In this study, the stability of PCM (phase change material) combined with drilling fluid as a coolant was discussed, and the influence of PCM on wellbore temperature field in drilling fluid was considered. A calculation model of temperature field of drilling fluid containing PCM was established, the cooling characteristics of PCM under the influence of different parameters were simulated, and the cooling effect of PCM integrated with drilling fluid on ultra-deep and high-temperature Wells was analyzed. The investigated PCM has a phase change temperature range of 120 ~ 130°C and a latent heat of 264.15 ~ 265.53 kJ/kg. Our results showed that the cooling impact of PCM exhibits an upward trend as the quantity of PCM utilized increases. Assuming the drilling temperature limit is 135°C, after adding 5% PCM to the drilling fluid, the drilling length of the horizontal section increased by approximately 500 m. With 15% PCM added, the horizontal section could be extended by about 1000 m. We conducted a simulation analysis on a well in southern Sichuan, and found that adding 12% PCM had the best cooling effect, reducing the bottom hole temperature by 12.3°C and extending the horizontal section by 700 m. Compared with conventional drilling fluid cooling methods, incorporating PCM as cooling agents within the drilling fluids provided better cooling effects. It effectively addressed the problem of excessive bottom-hole temperatures in deep wells, extended the drilling length of horizontal sections, and prolonged the service life of downhole instruments. Our research lays the groundwork for the future investigation of cooling techniques for high-temperature deep well drilling fluids.

Optimal rule based double predictive control for the management of thermal energy in a distributed clean heating system

Solar energy coupled with electric heat storage is a kind of promising energy saving technology for distributed building heating. Precise and quick heat load prediction for the demand side of heating system and renewable energy prediction for the supply side are imperative in realizing the flexibility of building clean energy supply systems. A predictive control based on back propagation (BP) artificial neural network is built to predict the demand heat load of an office building and the heat supply quantity of solar collector (SC) system. The heat dissipation of the SC system is considered to improve the prediction accuracy of its heat supply quantity. A double predictive (DP) control is introduced and combined with dynamic adjustment to optimize the operation of renewable energy, phase change heat storage and valley electric heating system. The results indicate that predictive model is of high precision and the variation coefficient of root mean squared errors corresponding to each prediction parameter are all greater than 0.9. Furthermore, the optimization results indicate that the DP control would save, in March, about 59.3% of charge heat quantity of phase change material (PCM) tank and terms of cost (30.4%). Meanwhile, maintaining indoor temperature between 20 °C and 22 °C.

Effect of Phase-Change Materials on Laboratory-Made Insoles: Analysis of Environmental Conditions.

Thermal comfort is essential when wearing a postural-corrective garment. Discomfort of any kind may deter regular use and prolong user recovery time. The objective of this work is therefore to optimize a new compound that can alter the temperature of orthopedic insoles, thereby improving the thermal comfort for the user. Its novelty is a resin composite that contains a thermoregulatory Phase-Change Material (PCM). An experimental design was used to optimize the proportions of PCM, epoxy resin, and thickener in the composite and its effects. A Box–Behnken factor design was applied to each compound to establish the optimal proportions of all three substances. The dependent variables were the Shore A and D hardness tests and thermogravimetric heat-exchange measurements. As was foreseeable, the influence of the PCM on the thermal absorption levels of the compound was quantifiable and could be determined from the results of the factor design. Likewise, compound hardness was determined by resin type and resin-PCM interactions, so the quantity of PCM also had some influence on the mechanical properties of the composite. Both the durability and the flexibility of the final product complied with current standards for orthopedic insoles.

Melting dynamics analysis of a multi-tube latent heat thermal energy storage system: Numerical study

This numerical study investigates the melting dynamics of paraffin wax as a phase change material (PCM) in a multi-tube latent heat thermal energy storage system (MT-LHTESS). The performance of an arrangement with four tubes is compared with a concentric single tube arrangement keeping the same cross-section area of heat transfer fluid tubes and the same PCM quantity. Four longitudinal fins of two types are also incorporated to further improve the melting. Thirteen cases with different arrangements of tubes and fins are compared in this study. The study attempts to select a suitable arrangement of the tubes. A two-dimensional enthalpy-porosity model in ANSYS-Fluent is used to solve the governing equations. The melting results are depicted as the contours of liquid fraction, temperature, and flow streamlines. The transient performance is assessed based on progress plots of liquid fraction and average domain velocity. It is observed that splitting into multiple tubes and using fins enhance the melting performance. The generation and coalescence of small vortices in the molten PCM accelerate the melting performance. The staggered array, larger eccentricity, and (+ type) finned tubes outperform their counterparts. The lowest melting time is observed in Case 2(+), having four staggered tubes, at 30 mm eccentricity, and with (+ type) fins. This case takes 75 min for complete melting, and 1411.1 kJ/m heat at a rate of 322 W/m is stored. The melting time gets reduced by 53.3–71.1% using four tubes and by 65.78–83.33% using finned four tubes as compared to the single tube case.

Energy, exergy, and economic assessment of thermal regulation of PV panel using hybrid heat pipe-phase change material cooling system

There has been a theoretical investigation for energy, exergy, and economic evaluation of thermal regulation of PV panels via an innovative hybrid cooling system of flat heat pipes (HPs) coupled with phase change material (PCM). PV panel dissipates its heat through the HP evaporator while the HP condenser is cooled by PCM. The cooling system performance is investigated for different PCM quantities and types (RT42, RT35HC, and SP31) for summer and (RT21, RT18HC, and SP15-gel) for winter conditions in Egypt. A thorough study and analysis have been conducted for the impact of the cooling system on PV panel's temperature, electric efficiency, output power, PCM energy storage, and system efficiency. The results show that compared with conventional PV, the best PCM type for PV performance in summer is SP31 of 3 cm thickness, which achieves a maximum PV temperature reduction of 20.6 °C with a maximum improvement in PV electric efficiency of 11.5%. SP15-gel of thickness 2.5 cm is the best PCM for winter conditions, achieving 14.1 °C temperature reduction with 7.2% enhancement in PV electric efficiency. The exergy efficiency of the PV panel is higher than in PCM, where it rises as the phase change temperature of the PCM increases. PV maximum average daily exergy efficiency is 13.4% for SP15-gel, compared with 12.71% for conventional PV in winter, while SP31 achieved 12.25%, 1% higher than reference PV in summer. PCM's maximum average daily exergy efficiency is 0.69% and 0.7% for RT42 and RT21 in summer and winter, respectively. The minimum payback period for conventional PV is about 18.01 years, while it is approximately 13.39 years for PV with HP and PCM. The studied cooling system at different PCMs proves its capability to enhance the PV performance with higher energy and exergy efficiencies and lower cost and store the excess heat inside the PCM.

Design, development, and performance testing of thermal energy storage based solar dryer system for seeded grapes

The deterioration of food crops after harvest can be prevented using the appropriate drying method. Solar energy can be used in several beneficial ways, and a solar-aided dryer is one of the prominent applications. A forced convection medium-sized solar dryer with Phase Change Material (PCM) was designed and fabricated for conducting drying experiments. Organic paraffin wax, a PCM, was used for thermal energy storage in the solar dryer. The PCM will enhance drying efficiency even during off sunshine hours and reduce the overall drying period. The study compares the drying performance characteristics of seeded grapes between open sun drying, solar drying without and with PCM(100 and 200 g). The results of the drying experiments showed that grapes were effectively dried out using the PCM-based solar dryer. The grapes dried in a shorter duration using a solar dryer with 200 g of PCM compared with other drying methods. The grapes were dried out from an initial moisture content of 80.2% to a final moisture content of about 18.6%. The prototype model of the solar dryer with PCM was recommended to limit the use of the workforce, avoid improper drying, and reduce the overall drying period. An increase in the quantity of PCM in the solar dryer reduced the overall drying time of the grapes. The outcomes revealed that PCM usage helped retain the chamber’s heat for a longer time than the test without PCM.

Eco-Friendly and Economical Solar Heater Design Using Internal Structure and Phase Change Materials

Indoor heating systems currently used are highly dependent on fossil fuels; hence, it is urgent to develop a new heating system to achieve carbon zero-emission. A solar air heater is eco-friendly because it generates nearly zero greenhouse gases. In this study, a parametric study was conducted for optimizing solar air heater design applicable to indoor heating. Installing the internal structure in the solar heater changes the interior flow characteristic, resulting in the air temperature increased by about 14.2 K on average compared to the heater without the internal structure. An additional case study was carried out to optimize the ideal quantity of phase change materials (PCM) in terms of mass fraction and heat capacity for various operating conditions. An excessive amount of PCM (e.g., 66% of the storage space filled with PCM) deteriorates the performance of the air heater unless the entire PCM could be melted during the daytime. After heating, the air temperature was maintained the longest when only 33% of the internal space was filled with PCM. The solar air heater can fully replace or partly assist a conventional heater for indoor heating, and it could reduce approximately 0.6 tCO2 per year.

Effect of encapsulation area on the thermal performance of PCM incorporated concrete bricks: A case study under Iraq summer conditions

In this paper, the thermal performance of phase change material (PCM) incorporated concrete bricks is studied experimentally. Four concrete bricks (three with macroencapsulated PCM and one without PCM represented the reference) are fabricated, and their thermal performance is tested under hot climate conditions. The study considered the effect of PCM encapsulation heat transfer area on brick's thermal performance at the same PCM quantity. PCM bricks included three different PCM capsule arrangements in which the first brick involved one bulky capsule (Brick-B, 4*4*10 cm3), the second brick had two capsules (Brick-C, 4*4*5 cm3), and the third brick involved five PCM capsules (Brick-D, 4*4*2 cm3). The peak temperature reduction (PTR), the conductive heat transfer reduction (HTRc), and the time delay (TD) were presented and calculated, taking into account the inner and outer brick surface temperatures of PCM bricks compared with the reference brick. Results showed that concrete bricks' thermal performance could be remarkably improved using PCM even under maximum outdoor temperatures. Moreover, the best thermal performance is reported for Brick-D, in which the maximum PTR, HTRc, and TD are reached 156.5 %, ∼61 %, and ∼133 %, respectively, compared with the reference brick under maximum outdoor temperatures.

Optimization of Solar Air Heater Design

Indoor heating systems currently used are highly dependent on fossil fuels; hence, it is urgent to develop a new type of heating system to achieve carbon zero emission. A Solar air heater is eco-friendly because it generates nearly zero greenhouse gases. In this study, a parametric study was conducted for optimizing solar air heater design applicable to indoor heating. The thermo-fluid dynamical characteristic of the solar air heater was analyzed by comparing the velocity of the air flow through the passage and the average exit temperature from the heater having different internal flow path structures. The average exit temperature can be increased by forming some path inside the heater. An additional case study was carried out to optimize the ideal quantity of phase change material (PCM) in terms of mass fraction and heat capacity for various operating conditions. Excessive amount of PCM deteriorates the performance of the air heater unless the entire PCM could be melted during the daytime. The solar air heater can fully replace or partly assist a conventional heater for indoor heating, and it could reduce approximately 0.6 tCO2 per year. These results are expected to provide useful information on the optimal design of solar air heaters.

Thermal performance of concrete bricks based phase change material encapsulated by various aluminium containers: An experimental study under Iraqi hot climate conditions

This study presents the experimental results of concrete bricks based macroencapsulated phase change material (PCM) in different capsule designs (circular, square and rectangular cross-sections). Eight concrete bricks (including a reference brick without PCM) are fabricated, and their thermal performance is tested under hot summer conditions of Al Amarah city, Iraq. The study considered several indicators such as the interior maximum temperature reduction (MTR), decrement factor (DF) and time lag (TL) to compared among tested bricks in addition to the thermal behaviour during melting and solidification of PCM. Results indicated that all PCM based bricks are performed better than the reference brick in which the maximum interior temperature is shaved and shifted. Moreover, the best thermal performance is reported for bricks of large PCM capsules number. Amongst others, the brick-based square cross-section PCM capsules showed the best thermal contribution where the average MTR of 1.88°C, average DF of 0.901 and average TL of 42.5 min were obtained compared with the reference brick. The study concluded that PCM capsules' heat transfer area is the main parameter that controls PCM's thermal behaviour as long as all PCM capsules have the same PCM quantity and position. Therefore, excessive encapsulation area might influence the thermal performance of concrete brick and should be specified for the efficient use of PCM storage capacity.

Photovoltaic Warm Façades with Phase Change Materials in European Climates

Since facade-integrated photovoltaic (PV) modules heat up greatly, which reduces the efficiency of thePV, facade panels with PV and phase change materials (PCM) were developed. PCMs absorb a significantamount of thermal energy during the phase transition from solid to liquid, while maintaining a specificmelting temperature. This cools down the PV and increases the electrical yield. Numerical studies onPV-PCM warm facades without rear-ventilation have so far been missing. Therefore, a thermal andan electrical simulation model for PV-PCM warm facades were developed and validated. They werethen used to analyse the yield increase of two PCM-types and -quantities in PV warm facades facingeast, south, and west in Athens, Potsdam, and Helsinki. An annual yield increase of 1.2% to 8.5% formonocrystalline PV modules was determined. The maximum monthly yield increase is 8.0% in Helsinki,11.4% in Potsdam, and 11.3% in Athens. The study shows that a case-specific selection of the appropriatetype and quantity of PCM is necessary. Using the models, a design tool for PV-PCM warm facades will bedeveloped. It will be validated with real monitoring data from PV-PCM facade test rigs at the TechnischeUniversitat Dresden and the National Technical University of Athens

Analysis and optimization of triple tube phase change material based energy storage system

We present an analysis and optimization of triple tube phase change material (PCM) based energy storage system. The study considers a triple tube energy storage system with PCM stored in the inner cylinder and outer annular region while heated water is passed through the inner annular region. Simulations are performed to analyze the effect of inner cylinder diameter on the total time required for complete melting of PCM while keeping the volume of PCM constant. Results show that the triple cylinder configuration leads to considerably faster melting as compared to the double cylinder system for the same mass flow rate of water and same quantity of PCM. It is found that the inner diameter, inlet temperature and mass flow rate of heat transfer fluid have considerable effect on the melting time while the effect of cylinder length is negligible. The main outcome of the study is that it shows that there exists an optimum diameter of the inner cylinder for which the melting rate is highest and considerably faster than that for the maximum and minimum diameter. Subsequent studies for different mass flow rates of water show that the optimum diameter does not vary significantly with change in mass flow rate.

Experimental and numerical analysis of the thermal performance of polyurethane foams panels incorporating phase change material

The potential thermal regulation effect of rigid polyurethane (RPU) foams can be enhanced by the incorporation of phase change materials (PCM). The main goal of the present work is to evaluate the thermal characteristics of RPU panels using two different types of PCM (a commercial one and another based on paraffin and calcium carbonate) and to quantify their potential as thermal regulators of indoor spaces.The experimental results obtained revealed that the RPU panels incorporating PCM can lead to a thermal amplitude reduction of about 3.5–1 °C (peak maximum temperature – peak minimum temperature). Furthermore, it was demonstrated that the performance of the RPU panel with PCM was enhanced when the external and internal mean temperature were closer to the melting peak temperature of the PCM. Additionally, it was also verified that the thermal amplitude reduction due to the PCM is more significant for the RPU panel incorporating PCM.In brief, the results showed that the efficiency of the RPU panels incorporating PCM is not exclusively dependent on the presence and quantity of PCM (equivalent in wt% in all cases) but it is also affected by the imposed temperature profile and the PCM thermal properties.

Enhanced thermal performance of a thermoelectric generator with phase change materials

Abstract In this article, a computational study of the thermal management of thermoelectric generator (TEG) with phase change materials (PCM) is made. The test model has been developed and studied using COMSOL Multiphysics. The thermal management of thermoelectric generator is studied using the heat sink encapsulating with the phase change materials through variations in the heat input and the quantity of PCM. The results showed the considerable reduction and constant maintenance with PCM for the cold side temperature of TEG. There was enhancement in output voltage due to an increase in the temperature difference between the hot and cold sides of TEG during the phase change period. The efficiency of TEG is enhanced due to improvement in voltage of TEG. The improvements in efficiency of TEG are found to be 36.7%, 33.8%, 30% for the heat inputs of 0.1 W, 0.15 W and 0.2 W respectively when the PCM height is 3 mm. From the computational results, it is confirmed that the PCM plays vital role for the enhancement in thermal performance of TEG.

Effect of phase change material plates' arrangements on charging and discharging of energy storage in building air free cooling

AbstractPrevious examinations of building air free cooling using phase change material (PCM) plates were numerically conducted for specific arrangements/configurations of PCMs plates. Experimental investigation for models validations and comparison between the different configurations of PCMs are the shortages of these studies. The present research experimentally investigates the effects of the PCM plate's arrangements on the thermal characteristics of the charging and discharging processes. Parallel and staggered arrangements of different spaces between the plates were tested. The effect of plates' arrangements on the discharging time and quantity of PCM needed to fulfill the required free cooling are also investigated. The results showed that (a) in parallel arrangement, the discharge time decreases with decreasing spaces between PCM plates; (b) the discharge time in staggered arrangement is longer than that of parallel arrangement by 63%; (c) putting PCM plates on large numbers of rows increases the discharge time; (d) in staggered arrangement, the discharge time increases with decreasing spacing between PCMs plates; (e) the needed quantity of PCMs plates in staggered arrangement is lower than that of parallel arrangement by about 67%; and (f) generally, staggered arrangement with low spaces between PCMs plates is the optimum arrangement for air free cooling as it has the longest discharge time.

Integration of solar charged PCM storage with VAR system for low capacity vegetable cold storage

In this work a solar-assisted vapour absorption refrigeration (VAR) system, suitable for 10 MT vegetable cold storage for a small village, has been modelled and analysed for day-night operation. Solar parabolic trough collector (PTC) has been considered for integration with a LiBr-H2O based VAR system. Thermal energy from solar thermal system is stored in a phase change material (PCM) energy storage, which is integrated with the VAR system. Apart from system integration, operational strategy of the storage based system has been evolved and performance of the system on hourly basis for representative days has been reported. The PCM quantity and the number of PTC modules have been decided based on the cooling demand. Hitec salt has been considered as PCM material. The study reveals that 5 PTC modules, each of 30 m2aperture area, and a PCM mass of 12.5 ton can effectively cater the energy demand of the VAR system to successfully maintain the 10 MT cold room at 6 °C.

Performance enhancement of unitary and packaged air conditioners with phase change material

A novel method of lowering condensing temperature of unitary and packaged air conditioners from 55 0C to around 45 0C is proposed with Phase Change Material (PCM) around the channels of Mini Channel Heat Exchanger (MCHE). Primary components of an air-conditioning system along with MCHE with PCM around its mini channels are modeled in MATLAB. A case study is performed considering the temperature-time profile of three Indian cities, viz. Bhopal, Jaipur, and Hyderabad to estimate the hourly energy consumption and saving in electrical energy input at various timings throughout the day, particularly in peak summer. Simulation results show that on an average there will be 15 to 25% reduction in power consumption with enhanced performance of an air conditioner throughout the year. Melting of PCM in MCHE begins at around 10.00 hours and continue up to around 22.00 hours during peak summer months depending on the geographical region and then onwards solidification begins and the entire PCM solidifies by around 10.00 hours depending on the temperature of air during the night. The maximum quantity of PCM required is estimated to be 375 kg per TR with latent heat of fusion of 201 kJ/kg.