Saurabh Tiwari

Bio: Saurabh Tiwari is an academic researcher from Indian Institute of Technology Bombay. The author has contributed to research in topics: Thermal energy storage & Hydride. The author has an hindex of 3, co-authored 7 publications receiving 50 citations.

Synthesis and characterization of CNTs using polypropylene waste as precursor

Abstract: We study the synthesis of MWCNTs using polypropylene waste as a precursor and Ni/Mo/MgO as a catalyst by the combustion technique. Molar ratios of Ni, Mo and MgO in the Ni/Mo/MgO catalyst were optimized using response surface methodology (RSM) to obtain the maximum yield of CNTs. The mole ratio 4/0.2/1 was found to yield more carbon product. Further, process parameters such as combustion temperature, combustion time, polymer and catalyst weight were optimized by RSM using Box–Behnken three-level and four-factorial design. The best possible combination of process parameters (combustion time of 10 min, combustion temperature of 800 °C, polymer weight of 5 g and catalyst weight of 150 mg) for maximum yield of CNTs was obtained. HRTEM indicates that the diameter of CNTs depends on the catalyst composition used for the synthesis of CNTs. The results of the study indicate a facile method for producing CNTs from polypropylene waste.

Optimization based methodology to design metal hydride reactor for thermal storage application

Abstract: A metal hydride based thermal energy storage system offers high energy density, provides longer storage time and requires less storage space compared to either conventional or phase change material based thermal energy storage systems. However, the design of such system is considered significantly complex. In this study, Taguchi method coupled with grey relational analysis was used to optimize the design parameters i.e. diameter of helical tube (dh), major diameter of helical tube (dm), number of turns of helical tube (N) and velocity of heat transfer fluid (Vf) for the helical tube heat exchanger embedded inside metal hydride reactor for thermal energy storage application. These parameters were optimized subjected to achieve maximum reaction fraction (C0) and maximum outlet temperature of heat transfer fluid (To). The performance of all experiments in the orthogonal array which were used for Taguchi and Grey relational analysis were evaluated by 3-D numerical simulations performed in commercial software COMSOL 5.3a. This methodology used is significantly computationally efficient as the number of required simulations reduced by 90% as compared to the conventional parametric study-based methodology. The required number of simulations reduced from 81 to 9 with the use of proposed methodology. Further, the added advantage of this methodology is, it enables to estimate an optimized level of the parameters by considering all the objective functions (C0, To) simultaneously. Lastly, the performance of the optimally designed systems was compared with all the orthogonal array experiments and it was found out that the optimized system designs were found to have better performance considering the objective parameters i.e., C0 and To as compared with the other experiments of the orthogonal array.

RoadCare: A Deep-learning Based Approach to Quantifying Road Surface Quality

Abstract: Roads form a critical part of any region's infrastructure. Their constant monitoring and maintenance is thus essential. Traditional monitoring mechanisms are heavy-weight, and hence have insufficient coverage. In this paper, we explore the use of crowd-sourced intelligent measurements from commuters' smart-phone sensors. Specifically, we propose a deep-learning based approach to road surface quality monitoring, using accelerometer and GPS sensor readings. Through extensive data collection of over 36 hours on different kinds of roads, and subsequent evaluation based on this, we show that the approach can achieve high accuracy (98.5%) in a three-way classification of road surface quality. We also show how the classification can be extended to a finer grained 11-point scale of road quality. The model is also efficient: it can be implemented on today's smart-phones, thus making it practical. Our approach, called RoadCare, enables several useful smart-city applications such as spatio-temporal monitoring of the city's roads, early warning of bad road conditions, as well as choosing the "smoothest" road route to a destination.

Comparative evaluation of circular truncated-cone and paraboloid shapes for thermal energy storage tanks based on thermal stratification performance

Abstract: In solar water heating systems, geometrical configurations of thermal energy storage (TES) play a crucial role in the enhancement of system performances. Upon conducting a thorough study on the influence of different shapes and aspect ratios of TES tanks, the present study focuses on the choice of suitable TES tank geometry based on the key performance parameters, viz. Richardson number, stratification number, storage efficiency and the initial thermocline thickness. Thermal stratification characteristics are investigated and analyzed in detail for three chosen shapes of TES, namely truncated-cone, paraboloid, and cylinder, using a two-dimensional unsteady numerical model. Results of the numerical model on cylindrical TES is found to have good agreement with the findings of the in-house experiments. With increasing aspect ratio (AR) of the paraboloid and truncated cone TES tanks, initial thermocline thickness and the energy losses increase, whereas, Richardson number and average stratification number decrease, indicating better stratification performance in storage tanks with lower AR. However, there is a limit on reducing the AR. At every AR investigated for the two shapes of TES, Richardson number for the paraboloid TES is greater than that of the truncated-cone TES, qualitatively suggesting a better temperature stratification in the paraboloid TES. The effect of flow rate on the thermal stratification characteristics is also studied, which suggests that increasing the flow rate enhances mixing and deteriorates stratification. The findings can be used as guidelines for designing TES with improved thermal performance.

Design of metal hydride reactor with embedded helical coil using optimization methods

Abstract: Metal hydride offers an efficient and cost-effective method to store hydrogen. In this study, Taguchi method coupled with grey relational analysis was used to optimize the design parameters i.e., diameter of helical tube (dh), major diameter of helical tube (dm), number of turns of helical tube (N) and velocity of heat transfer fluid ( V f ) for the helical tube heat exchanger embedded inside metal hydride bed to achieve minimum desorption time (td) for 80% desorption and minimum outlet temperature (T0) of heat transfer fluid (HTF). The performance of all experiments in the orthogonal array used for Taguchi and Grey relational analysis was evaluated by 3-D numerical simulations performed in commercial software COMSOL 5.3a. This stepwise methodology is significantly computationally efficient as the number of required simulations reduced by 90% as compared to the traditional parametric study-based methodology. Further, this methodology enables to estimate an optimized level of the parameters by considering all the objective functions (td, T0) simultaneously. Later, the performance of the optimally designed systems was compared with the orthogonal array experiments and it was found out that the optimized system designs have better performance in terms of the objective parameters i.e., td and T0 when compared with the other experiments of orthogonal array. These optimized systems will then be used for refrigeration and cooling applications.

Road traffic injuries.

Abstract: The appearance of cars has raised materialistic civilization and living standard to an unprecedented level. Today, it is hard to imagine how we human beings can live without cars. Yet, motor vehicles can cause a great number of deaths and injuries as well as considerable economic losses, which have constituted the global burden. Understanding of the occurrence and development of road traffic injuries will contribute to the prevention and control of crash and to the implementation of "everybody has the right to enjoy health" proposed by WHO.