Investigation of Dynamic Thermal Parameters of Various Insulation Filled Bricks Exposed to Periodic Thermal Variations for Energy Efficient Stuffed Bricks Design

The space cooling systems account for nearly 30% of energy consumption in India. The highly insulated external walls are essential prerequisites for low energy consumption of buildings. Filling shell of the brick with insulation material is one of the methods to reduce cooling loads in buildings. This paper aims to investigate the dynamic thermal parameters of various insulation filled bricks. The dynamic thermal parameters highlighted in the study include thermal transmittance, admittance, decrement factor, time lag and areal thermal heat capacity. The cyclic admittance method was employed in computer simulation program to compute dynamic thermal parameters of stuffed bricks. The four brick materials such as mud bricks, burnt bricks, concrete blocks and fly ash bricks were selected. The insulation materials used for filling shells of the brick are foam glass and asbestos fibre. The total forty eight stuffed bricks were investigated. The shell of the brick is filled by the insulation and the each layer of insulation is separated by a brick web. The shell and web thickness of the brick were maintained as per the Indian standards. The six configurations of the stuffed bricks were investigated (1. Solid brick, 2. Bricks with the shell of the brick filled with single layer of insulation, 3. Bricks with the shell of the brick filled with two layers of insulation with each insulation layer separated with a brick web, 4. Bricks with the shell of the brick filled with three layers of insulation with each insulation layer separated by a brick web, 5. Bricks with the shell of the brick filled with four layers of insulation with each insulation layer separated by a brick web and 6. Bricks with the shell of the brick filled with five layers of insulation with each insulation layer separated by a brick web). From the results, it is observed that the stuffed bricks significantly improve time lag values as compared to the conventional solid bricks. The decrement factor decreases, admittance increases and areal thermal heat capacity increases with the increase in the number of insulation layers in the bricks. The concrete blocks with the shell of the bricks filled with five layers of asbestos fibre insulation offer the highest admittance (3.11W/m2K), the lowest decrement factor (0.435), the highest time lag values (8.26 h) and the highest areal thermal heat capacity (57366 J/m2K) among all insulation filled bricks studied. The results of the paper help in designing energy efficient stuffed bricks which can be used for construction of buildings and thereby reducing cooling loads

Effect of Window Overhang Shade on Heat Gain of Various Single Glazing Window Glasses for Passive Cooling

AbstractThis paper presents thermal performance of various single glazing window glasses covered with and without window overhang shading. Buildings are designed with laterite stone walls with different dimensions of overhang shading devices on single glazing windows in four different climatic zones of India: Ahmedabad (Hot & dry), Bangalore (moderate), Calcutta (warm & humid) and Hyderabad (composite). In this study, five glass materials such as clear, bronze, green, grey and blue-green were selected. Total three hundred and twenty building models with and without window overhangs were designed in four climatic zones of India using Design builder 4.3.0.039. Thermal simulation was carried out in Energy plus 8.1 simulation tool. From the results, it is observed that laterite buildings with grey glass window with 1.5m overhang shading device were found to be energy efficient from the least heat gain point of view in south direction among three hundred and twenty building models studied in four climatic zones of India. The results of the study help in selecting the best window glass material and also help in selecting appropriate dimensions for overhang shading device for reducing cooling loads in buildings

Solar salt with carbon nanotubes as a potential phase change material for high-temperature applications: Investigations on thermal properties and chemical stability

Nano-enhanced phase change materials are highly employed for an enhanced heat-transfer process. The current work reports that the thermal properties of solar salt-based phase change materials were enhanced with carbon nanotubes (CNTs). Solar salt (60:40 of NaNO3/KNO3) with a phase change temperature and enthalpy of 225.13 °C and 244.76 kJ/kg, respectively, is proposed as a high-temperature PCM, and CNT is added to improve its thermal conductivity. The ball-milling method was employed to mix CNTs with solar salt at various concentrations of 0.1, 0.3, and 0.5% by weight. SEM images display the even distribution of CNTs with solar salt, with the absence of cluster formations. The thermal conductivity, phase change properties, and thermal and chemical stabilities of the composites were studied before and after 300 thermal cycles. FTIR studies indicated only physical interaction between PCM and CNTs. The thermal conductivity was enhanced with an increase in CNT concentration. The thermal conductivity was enhanced by 127.19 and 125.09% before and after cycling, respectively, in the presence of 0.5% CNT. The phase change temperature decreased by around 1.64% after adding 0.5% CNT, with a decrease of 14.67% in the latent heat during melting. TGA thermograms indicated the weight loss was initiated at about 590 and 575 °C before and after thermal cycling, after which it was rapid with an increase in temperature. Thermal characterization of CNT-enhanced solar salt indicated that the composites could be used as phase change materials for enhanced heat-transfer applications

Thermal and energy analysis of a novel solar updraft tower design with divergent chimney and convergent collector concept: CFD analysis with experimental validation

The fact that energy sources are heavily dependent on fossil fuels increases the need for alternative energy day by day. Solar energy is the most popular alternative energy source with massive potential. Solar chimney power plants (SCPP) are one of the systems of interest based on solar energy. SCPP systems are rare systems that can provide 24-hour power output. Their performance has been the subject of constant research since the first pilot plant in Manzanares. Design is crucial for performance figures of SCPPs, and the limitation of climatic parameters causes the system to be approached with different designs. This study makes a 3D CFD model by combining the divergent chimney and convergent collector structure based on the first pilot plant. The solar ray tracing algorithm and the RNG k-e turbulence model are applied and the model equations are solved under dynamic conditions with the reliable software ANSYS FLUENT. After the mesh-independent solution of the model is complete, it is validated with experimental data. The two cases are compared for solar radiation of 1000 W/m2 and environmental temperature of 293 K. A power output of 50.51 kW is achieved for standard pilot sizing. With the new model, the power output rises to 146.34 kW. It is seen that the divergent chimney and convergent collector affect the airflow in the system, increasing the maximum air velocity to 19.363 m/s. In parallel with the experimental data, it is seen that the temperature on the ground exceeds 360 K in the CFD results

Experimental performance assessment of a novel insulation plaster as an energy-efficient retrofit solution for external walls: A key building material towards low/zero carbon buildings

Thermal insulation plasters have become the focus of attention in the building sector. Among the most important reasons for this is the high thermal energy losses of the buildings. Since conventional briquettes used in buildings allow high heat transfer, the construction industries are looking for alternative insulation ways with low cost and high thermal efficiency. The use of insulation plasters is becoming popular due to the high cost and installation of insulation materials such as Expanded Polystyrene (EPS), which is among the alternative ways. Therefore, in this study, the novel insulation plaster (NIP) developed in contrast to traditional insulation plasters is tested on conventional briquettes in different thicknesses. On considering the total heat transfer coefficient (U-value), it is understood that whilst the conventional briquette has the highest value with approximately 5.5 W/m2K, the briquette with 2-2 NIP thickness has the lowest value with a value of almost 2.86 W/m2K. As a result of the tests, the total heat transfer coefficient of the briquette with 1-1 NIP thickness is observed to have an improvement of nearly 22.5% compared to conventional briquettes, while a progress of approximately 36.4% is seen in briquettes with 2-1 NIP thickness. In addition, it is revealed that the best mitigation in the overall heat transfer coefficient is about 47.9% in briquettes with 2-2 NIP thickness. It is also figured out that NIP has additional thermal durability thanks to the dead air pores and boron minerals in its internal structure

Optimizing soybean biofuel blends for sustainable urban medium-duty commercial vehicles in India: an AI-driven approach

This article presents the outcomes of a research study focused on optimizing the performance of soybean biofuel blends derived from soybean seeds specifically for urban medium-duty commercial vehicles. The study took into consideration elements such as production capacity, economics and assumed engine characteristics. For the purpose of predicting performance, combustion and emission characteristics, an artificial intelligence approach that has been trained using experimental data is used. At full load, the brake thermal efficiency (BTE) dropped as engine speed increased for biofuel and diesel fuel mixes, but brake-specific fuel consumption (BSFC) increased. The BSFC increased by 11.9% when diesel compared to using biofuel with diesel blends. The mixes cut both maximum cylinder pressure and NOx emissions. The biofuel-diesel fuel proved more successful, with maximum reduction of 9.8% and 22.2 at rpm, respectively. The biofuel and diesel blend significantly improved carbon dioxide (CO2) and smoke emissions. The biofuel blends offer significant advantages by decreeing exhaust pollutants and enhancing engine performance

Optimizing soybean biofuel blends for sustainable urban medium-duty commercial vehicles in India: an AI-driven approach

This article presents the outcomes of a research study focused on optimizing the performance of soybean biofuel blends derived from soybean seeds specifically for urban medium-duty commercial vehicles. The study took into consideration elements such as production capacity, economics and assumed engine characteristics. For the purpose of predicting performance, combustion and emission characteristics, an artificial intelligence approach that has been trained using experimental data is used. At full load, the brake thermal efficiency (BTE) dropped as engine speed increased for biofuel and diesel fuel mixes, but brake-specific fuel consumption (BSFC) increased. The BSFC increased by 11.9% when diesel compared to using biofuel with diesel blends. The mixes cut both maximum cylinder pressure and NOx emissions. The biofuel-diesel fuel proved more successful, with maximum reduction of 9.8% and 22.2 at rpm, respectively. The biofuel and diesel blend significantly improved carbon dioxide (CO2) and smoke emissions. The biofuel blends offer significant advantages by decreeing exhaust pollutants and enhancing engine performance. Graphical Abstract: (Figure presented.)

Influence of injection pressure on the dual-fuel mode in CI engines fueled with blends of ethanol and tamanu biodiesel

DATA AVAILABILITY : The data used to support the findings of this study are included within the article.The acceleration of global warming is primarily attributable to nonrenewable energy sources such as conventional fossil fuels. The primary source of energy for the automobile sector is petroleum products. Petroleum fuel is depleting daily, and its use produces a significant amount of greenhouse emissions. Biofuels would be a viable alternative to petroleum fuels, but a redesign of the engine would be required for complete substitution. The use of CNG in SI engines is not new, but it has not yet been implemented in CI engines. This is due to the fuel having a greater octane rating. The sole use of CNG in a CI engine results in knocking and excessive vibration. This study utilizes CNG under dual-fuel conditions when delivered through the intake manifold. In a dual-fuel mode, compressed natural gas (CNG) is utilized as the secondary fuel and a blend of 90% tamanu methyl ester and 10% ethanol (TMEE10) is used as the primary fuel. The injection pressure (IP) of the primary fuel changes between 200 and 240 bar, while the CNG induction rate is kept constant at 0.17 kg/h. The main combustion process is governed by the injection pressure of the pilot fuel. It could be affecting factors such as the vaporization characteristics of the fuel, the homogeneity of the mixture, and the ignition delay. Originally, tamanu methyl ester (TME) and diesel were used as base fuels in the investigation. As a result of its inherent oxygen content, TME emits more NOx than diesel. The addition of 10% ethanol to TME (TMEE10) marginally reduces NOx emissions in a CI mode because of its high latent heat of vaporization characteristics. Under peak load conditions, NOx emissions of TMEE10 are 6.2% lower than those of neat TME in the CI mode. Furthermore, the experiment was conducted using TMEE10 as the primary fuel and CNG as the secondary fuel. In the dual-fuel mode, the TMEE10 blend showed higher combustion, resulting in an increase in performance and a significant decrease in emission characteristics. As a result of the CNG’s high-energy value and rapid burning rate, the brake thermal efficiency (BTE) of TMEE10 improves to 29.09% compared to 27.09% for neat TME. In the dual-fuel mode of TMEE10 with 20.2% CNG energy sharing, the greatest reduction in fuel consumption was 2.9%. TMEE10 with CNG induction emits 7.8%, 12.5%, and 15.5% less HC, CO, and smoke, respectively, than TME operation.http://www.hindawi.com/journals/ijce/am2023Mechanical and Aeronautical Engineerin

4E analysis of a two-stage refrigeration system through surrogate models based on response surface methods and hybrid grey wolf optimizer

Refrigeration systems are complex, non-linear, multi-modal, and multi-dimensional. However, traditional methods are based on a trial and error process to optimize these systems, and a global optimum operating point cannot be guaranteed. Therefore, this work aims to study a two-stage vapor compression refrigeration system (VCRS) through a novel and robust hybrid multi-objective grey wolf optimizer (HMOGWO) algorithm. The system is modeled using response surface methods (RSM) to investigate the impacts of design variables on the set responses. Firstly, the interaction between the system components and their cycle behavior is analyzed by building four surrogate models using RSM. The model fit statistics indicate that they are statistically significant and agree with the design data. Three conflicting scenarios in bi-objective optimization are built focusing on the overall system following the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and Linear Programming Technique for Multidimensional Analysis of Preference (LINMAP) decision-making methods. The optimal solutions indicate that for the first to third scenarios, the exergetic efficiency (EE) and capital expenditure (CAPEX) are optimized by 33.4% and 7.5%, and the EE and operational expenditure (OPEX) are improved by 27.4% and 19.0%. The EE and global warming potential (GWP) are also optimized by 27.2% and 19.1%, where the proposed HMOGWO outperforms the MOGWO and NSGA-II. Finally, the K-means clustering technique is applied for Pareto characterization. Based on the research outcomes, the combined RSM and HMOGWO techniques have proved an excellent solution to simulate and optimize two-stage VCRS

Nano-refrigerants and nano-lubricants in refrigeration : synthesis, mechanisms, applications, and challenges

Addressing global energy security and environmental concerns, the utilization of nano-refrigerants and nano-lubricants has emerged as an innovative path for enhancing heat transfer. This research focuses on enhancing the thermophysical properties, heat transfer efficiency, and tribological characteristics of nanofluids—nanoparticles dispersed in refrigerants or lubricants. These nanofluids have demonstrated significant potential in applications such as cooling, air conditioning systems, and heat transfer equipment including pumps and pipes. A comprehensive understanding of parameters like thermal conductivity, viscosity, pressure drop, pumping power, and energy performance is delivered, with the aim of enhancing the overall efficiency of refrigeration systems, particularly the coefficient of performance (COP). Additionally, the review covers existing research on flow and pool boiling heat transfer, nano-lubricant tribological enhancement, and nano-refrigerant condensation. The study also addresses the challenges associated with the use of nano-refrigerants and nano-lubricants and offers a prospective outlook for their usage. These novel nanofluids are anticipated to emerge as effective solutions for increasing the COP and reducing energy consumption in the industrial sector, thus extending beyond the scope of previous efforts in this field. This review could serve as a valuable resource for a broad audience interested in this novel approach to energy efficiency