• Energy Research
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Abstract Gold nanoparticles (Au-NPs) seeded plasmonic nanofluids (PNFs) have shown promising results in overall performance enhancement of direct absorption solar collector (DASC) due to localized surface plasmon resonance (LSPR) effect. For the work presented here, Au-NPs were synthesized by the wet chemical method and were utilized to prepare plasmonic nanofluid. The surface plasmon resonance peak of Au-NPs was observed at 531 nm using UV–Visible spectrophotometer study. The testing for performance enhancement of gold plasmonic nanofluid (GPNF) laden DASC so far is limited to laboratory scale setups or simulation studies. Considering the dearth of outdoor experimental studies, an attempt has been made in the present study to evaluate the thermal performance of Au-NPs (∼40 nm) based nanofluid (∼0.0002 wt%) in full scale DASC. The experiments have been performed at different flow rates under clear sky outdoor conditions in winter season at Jalandhar, India. The maximum collector outlet temperature was measured to be 55 °C with GPNF which is about 7 °C higher than the maximum outlet temperature obtained with de-ionized water as working fluid. Thermal efficiency with GPNF is about 33% higher than de-ionized water at the optimal flow rate of 0.030 kg/s.

In the present world, renewable sources of energy have begun to make a significant contribution to meeting heat and power needs. In India, the Government is implementing a wide ranging programmes on renewable energy technologies. Several policy and fiscal measures have contributed to the rapid expansion of the progress during the last few years. This paper presents a review of renewable energy programme and vision in India. The present situation is seen to be much more promising and favourable for renewables.

Abstract In the three-pressure vapour absorption refrigeration system analysed here, a pressure control valve is introduced between the generator and the condenser of the conventional two-pressure system. This permits the generator to operate at higher pressures than those at the condenser. A comparative study is made of the performance of four working fluids namely, R22-DMF, R22-DMETEG, R21-DMF and NH 3 NaSCN. It is observed that this cycle yields higher coefficients of performance than the conventional absorption cycle even though at the penalty of higher pump work. Such systems seem to be especially attractive when low condensing temperatures are possible and relatively high temperature heat sources (e.g. concentrators, advanced flat plate collectors) are available.

Abstract The investigation first time reports the efficacy of de-oiled algal biomass extract (DOABE) for mixotrophic cultivation of Chlorella sp. MCC27 to enhance biodiesel production in open tray systems and in BioXpert-V2 software connected photobioreactor (PBR). The cultivation systems with addition of DOABE (PBR systems + DOABE and open tray system + DOABE) as media were tested for quality and quantity of biodiesel. The presence of organic carbon and low nitrogen in DOABE caused >2 folds higher biomass productivity and >4 folds enhanced lipid productivity for the cells cultivated in PBR system + DOABE and open tray system + DOABE as compared to control (i.e. BBM). Biochemical analysis of cells from both the systems revealed the decrease in total carbohydrates and protein contents. The FAMEs analyses showed vehicular quality biodiesel. PBR system + DOABE showed edge over open tray system + DOABE in terms of biomass productivity and lipid content. The physical properties of biodiesel produced from Chlorella sp. MCC27 were more close to the fuel standards (ASTM D6751), when cells were cultivated in open tray system + DOABE than in PBR system + DOABE. Collectively, this study highlights the use of DOABE as a low cost feedstock for enhancing vehicular quality biodiesel production from microalgae.

The objective of this work is to assess the combined effects of fixed pressure drop and specific air mass flow rate on duct dimensions (length and depth) of single-pass-with-bare-plate, single-cover and double-cover solar air heaters, and to obtain the resultant system efficiency that corresponds to a pre-fixed pumping cost and a minimum material cost per unit area of the system. The design selection methodology adopted in this paper will make it feasible for an air-heater designer to construct efficient and economical solar air heaters.

Abstract The purpose of this study is to evaluate the potential of isolated novel bacterial strains for rice straw (RS) hydrolysis in terms of total sugar and COD (chemical oxygen demand) solubilization to improve overall biomethane yield. Four out of seven pretreatment setup with isolated bacterial strains i.e., Bacillus paralicheniformis VKVVG3 (CDf), Perlucidibaca piscinae VKVVG6 (CDd1), Bacillus clausii VKAK2 (RSa1) and Bacillus mojavensis VKAK1 (CDb1) exhibited higher saccharification compared to untreated RS. The CDf pretreated RS showed highest efficiency with 137% COD solubilization and 320% sugar accumulation at optimal dosage of 109 CFU/mL within 4-day of incubation. The batch reactor (20L) study with CDf pretreated RS produced 476 mL/g VSsubstrate compared to 310 mL/g VSsubstrate for untreated RS which corresponds to 53.6% higher than untreated RS. The FESEM, FTIR, and XRD analysis also support the overall results, indicating excellent degradation of the structural morphology of the RS microcrystalline structure. Furthermore, the fitting error in bio-kinetic parameters using modified Gompertz, Fitzhugh, and Monomolecular models were 5.47, 2.44, and 4.28% respectively, with R2 values above 0.99, also supports the experimental data. The results of this study revealed many positive interpretations concerning the future expansion of the existing system for bacterial pretreatment of RS.

Abstract Generation of hot spot, due to partial shading and other mismatch conditions, is associated with photovoltaic (PV) systems since its very early applications in satellites, but a simple, economic and effective solution is still unavailable. Conventional hot spot mitigation technique, using a bypass diode (BPD) across each sub-panel, reduces the reverse bias voltage only up to −12 V to −19 V across the shaded cell, which matches exactly with the voltage range at which avalanche breakdown of PV cells occur. Reverse breakdown of an acidic texturized PV cell occurs merely at −13 V and between −15 V and −20 V for alkaline texturized ones. Hence, the standard BPD based circuit is not effective enough in preventing reverse breakdown of PV cells and hot spot generation. In this paper, a modified bypass circuit is proposed which successfully strikes a balance between the increase in reliability through reduction of hot spot temperature and increase in complexity of bypass circuit. The experimental study and simulation reveal that the proposed bypass circuit effectively reduced hotspot temperature of the obscure cell below average temperature of the module, without increasing the power loss, system complexity and cost thereof, substantially.

Abstract The government of India is promoting renewable energy sector with an ambitious target of 175 GW capacity, to be achieved by 2022. The reasons for this energy transition from fossils to renewable energy technologies include facilitating energy access, promoting cleaner forms of energy and enhancing energy security. The huge capacity shall require about 200,000 ha of land. However, land procurement has been identified as a key impediment in accelerating the growth of renewable energy sector in India. This presents an exciting business opportunity towards setting up community energy projects under community mode with the local people as shareholders. Community members can provide their land for setting up renewable energy projects as well as support in project development activities in lieu of getting upto 15% equity participation. This shall provide them with a constant source of income, estimated at over US $ 4000 per hectare per annum, besides facilitating energy access in villages. Quicker possession of land shall expedite project execution and the reduced capital expenditure shall decrease the cost of energy generation by upto 6%. Policy makers in emerging economies like India can pilot the proposed model in upcoming solar parks and wind farms.

Abstract An integral type natural convection solar drier has been fabricated and coupled with a biomass stove. Experiments have been conducted to test the performance of the drier by drying of Zingiber officinale (ginger), Curcuma longa l. (turmeric) and Tinospora cordifolia (guduchi) during the summer climate in Delhi. It was found that, during the load test for ginger, 18 kg of fresh product with an initial moisture content of 319.74(db)% was dried to a final moisture content of 11.8(db)% within 33 h. Similarly, moisture content of turmeric and guduchi were reduced from 358.96 to 8.8 and 257.45 to 9.67(db)% during 36 and 48 h of drying, respectively. The drying of these products has also been studied under ‘solar-only’ and open sun in the same climatic conditions and the results indicate that for all the products, drying is faster, and is within 33–48 h in hybrid drier, against 72–120 h in ‘solar-only’ operation of the same drier and 192–288 h in open sun. Efficiency of the drier during its two mode (solar and biomass separately) of operation has been estimated and quality evaluation of under-studied products showed that developed drier is suitable for the drying of these products. The developed drier is a simple system, which can be manufactured locally and can be used for drying of other agricultural products.