Solar Energy 208 (2020) 1114–1150 Available online 4 September 2020 0038-092X/© 2020 International Solar Energy Society. Published by Elsevier Ltd. All rights reserved. A comprehensive analysis on advances in application of solar collectors considering design, process and working fuid parameters for solar to thermal conversion Sujit Kumar Verma a, * , Naveen Kumar Gupta a , Dibakar Rakshit b a Department of Mechanical Engineering, Institute of Engineering and Technology, GLA University Mathura, 281406, India b Centre for Energy Studies, Indian Institute of Technology, IIT Delhi, India A R T I C L E INFO Keywords: Design aspects Solar collector Selective materials Flow inserts Thermal effciency ABSTRACT Presented review is an attempt to analyze progressive enhancement in performance of solar collectors in view of changes in design of collector components, changes and modifcations in process parameters and advances in working fuid produced by addition of nano-particles in base fuid of water or oil. Observations based on con- tributions of many researcher’s shows that design, process and working fuids have functional relationship among them which resulted in improved working effciency. Optimization of these parameters will lead to highest thermal effciency. The presented review is focused on synergistic approaches, processes, design crite- rions and advances in working fuids to achieve optimum thermal and exergy effciency for solar collectors mainly fat plate solar collectors, evacuated tube collectors and concentrating collectors. Recent trends that has been witnessed as steadily upward growth, reveals that incorporation of modern working fuid along with phase changing materials embedded with nanoparticles and compatible design changes can produce optimized results. On the basis of comprehensive analytical investigation of published works by many researchers, valuable con- tributions from scientists and engineers it can be interpreted that design modifcation, suitable working fuids along with phase changing materials can further make solar collectors more versatile in terms of application in water heating, process heating, power generation and integration of these devices in buildings and agricultural works. 1. Introduction: Flat plate solar collectors are simplest, cost effective and popular solar energy harvesting systems. Progressive advancement in fat plate solar collector has been contributed by modifcation in design, insu- lation material, process improvement and advanced working fuids (nano-fuids) of vast varieties. Any change in one parameters may bring about compatible changes in other parameters. Technological advances and engineering modifcations always provides opportunity to make existing system more effcient by reducing losses in energy, reducing cost of material and maintenance cost. Contemporary world facing greatest threat from consequences of haphazard development that has been going on since frst industrial revolution. Environmental & ecological imbalance has reached to a level where drastic and unifed efforts are needed address it. There has been a general awareness among nations and people to think and act seriously to address this menace and take effective decisions to achieve tangible results in terms of reduction in energy demands from conventional energy sources. In coming years’ cleaner energy production along with reduced material consumption will become a new modern index of development. Renewable energy resources are either free from carbon emission or carbon neutral in whole life cycle. Among various renewable resources, Solar energy is torch bearer because of its universality and emission free resource. Solar energy can be harvested by two routes as shown in Fig. 1. One is direct conversion of solar energy into electricity by photovoltaic cell. By thermal route we use heating value enriched spectrum of solar radiation for heating of water for process heating or by using concentrating collectors for elec- trical energy production through running of steam turbines. Routes of Solar energy harvesting are demonstrated in schematic Fig. 1.Beauty of fat solar collectors lies in its versatility of use and it can work with both direct and diffused radiation. Renewable energy resources can be used in heating of greenhouses during winter to save conventional energy and * Corresponding author. E-mail address: sujit.verma@gla.ac.in (S.K. Verma). Contents lists available at ScienceDirect Solar Energy journal homepage: www.elsevier.com/locate/solener https://doi.org/10.1016/j.solener.2020.08.042 Received 1 June 2020; Received in revised form 12 August 2020; Accepted 14 August 2020