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C. Chiranjeevi

Bio: C. Chiranjeevi is an academic researcher from VIT University. The author has contributed to research in topics: Desalination & Solar humidification. The author has an hindex of 7, co-authored 15 publications receiving 181 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, a two-stage humidification and dehumidification (HDH) desalination system has been extended with cooling system integration, which results in an overall high energy utilization factor (EUF) compared to the single output system.

56 citations

Journal ArticleDOI
TL;DR: In this article, convective heat transfer analysis for a horizontal circular pipe with fluid in mixed laminar flow range is performed using experimental simulation under constant heat flux boundary condition, and the variation of heat transfer coefficient and pressure drop in the pipe flow for water and water based Al2O3 nanofluids at different volume concentrations and twisted tapes are studied.

55 citations

Journal ArticleDOI
TL;DR: In this article, a two-stage HDH integrated cooling plant has been developed and analyzed with experimental and simulation studies and the simulated results developed for subsystems are validated with the experimental readings.

47 citations

Journal ArticleDOI
TL;DR: In this article, the authors compared the merits of the proposed HDH desalination and cooling are not analyzed and compared in the literature and recommended the use of chilled water in the final stage.
Abstract: Humidification–dehumidification (HDH) desalination works based on a water cycle principle and involves air humidification and condensation (dehumidification). The cooling of humid air with chilled water increases the desalination and results in cold air suitable for air conditioning process. The merits of the proposed HDH desalination and cooling are not analyzed and compared in the literature. Therefore, the performance results of HDH with normal water (current technology) and HDH with chilled water (proposed idea) are compared to highlight the merit of this cycle. The combined cycle for desalination and cooling has been solved thermodynamically with psychrometric properties. The results are validated with a laboratory experimental setup. The examined operational process conditions are hot water inlet temperature, efficiency of humidifier, and vapor absorption refrigerator's (VAR's) evaporator exit temperature. The focused results are desalination, cooling and energy utilization factor (EUF). The comparative study recommends the use of chilled water in the final stage. The two stage desalination with dehumidification by normal water in the first stage and chilled water in combined two stages improves the cycle EUF from 0.18 to 0.33. Out of 300 W of cooling generation, 100 W is used for dehumidification and the remaining 200 W is available for air conditioning process at 15 N⋅m 3 h −1 of air.

35 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the authors present empirical and numerical analyses of thermal performance development in flat plate solar collectors (FPSCs) and provide a complete overview of the up-to-date developments, methods, critical economic factors, the significance of solar water heating, and the challenges faced by the implementations of such solar energy heating systems.

262 citations

09 Jul 2018
TL;DR: A review of the state of the art and the current research activities of high temperature heat pumps with heat sink temperatures in the range of 90 to 160°C can be found in this paper.
Abstract: Abstract This study reviews the current state of the art and the current research activities of high temperature heat pumps (HTHPs) with heat sink temperatures in the range of 90 to 160 °C. The focus is on the analysis of the heat pump cycles and the suitable refrigerants. More than 20 HTHPs from 13 manufacturers have been identified on the market that are able to provide heat sink temperatures of at least 90 °C. Large application potentials have been recognized particularly in the food, paper, metal and chemical industries. The heating capacities range from about 20 kW to 20 MW. Most cycles are single-stage and differ primarily in the refrigerant (e.g. R245fa, R717, R744, R134a or R1234ze(E)) and compressor type used. The COPs range from 2.4 to 5.8 at a temperature lift of 95 to 40 K. Several research projects push the limits of the achievable COPs and heat sink temperatures to higher levels. COPs of about 5.7 to 6.5 (at 30 K lift) and 2.2 and 2.8 (70 K) are achieved at a sink temperature of 120 °C. The refrigerants investigated are mainly R1336mzz(Z), R718, R245fa, R1234ze(Z), R600, and R601. R1336mzz(Z) enables to achieve exceptionally high heat sink temperatures of up to 160 °C.

246 citations

Journal ArticleDOI
TL;DR: In this article, a review of the literature on the area of heat transfer improvement employing a combination of nanofluid and inserts is performed, and the progress made and current challenges for each combined system are discussed, and some conclusions and suggestions are made for future research.
Abstract: Improving heat transfer is a critical subject for energy conservation systems which directly affects economic efficiency of these systems. There are active and passive methods which can be employed to enhance the rate of heat transfer without reducing the general efficiency of the energy conservation systems. Among these methods, passive techniques are more cost-effective and reliable in comparison with active ones as they have no moving parts. To achieve further improvements in heat transfer performances, some researchers combined passive techniques. This article performs a review of the literature on the area of heat transfer improvement employing a combination of nanofluid and inserts. Inserts are baffles, twisted tape, vortex generators, and wire coil inserts. The progress made and the current challenges for each combined system are discussed, and some conclusions and suggestions are made for future research.

191 citations

Journal ArticleDOI
TL;DR: In this paper, the authors developed a thermodynamic model framework to analyse the performance of a parabolic trough collector with a twisted tape insert, and they found the set of conditions under which a twisted-tape insert is useful to boost the performance.

164 citations

Journal ArticleDOI
TL;DR: In this paper, a review on work done in the area of heat transfer augmentation using twisted tapes has been carried out and the optimum shape for twisted tapes can also be developed based on maximisation of heat and minimisation of friction factor regarding fluid used in the system.
Abstract: Heat transfer enhancement is an important matter of concern for energy conservation and also beneficial from economic point of view. The use of passive devices like twisted tapes, roughness elements, wires inserts etc. are effective methods of heat transfer augmentation. Many research studies on different types of twisted tapes geometries to increase heat transfer rate have been carried out. Also, several correlations were developed to determine heat transfer and friction factor for twisted tape inserts. In the present study, a review on work done in the area of heat transfer augmentation using twisted tapes has been carried out. Previous experimental and numerical studies on various types of twisted tapes (based on the literature survey) were discussed. These studies reveal that the future research in the area of twisted tapes will bring more development in the heat exchanger systems. The optimum shape for twisted tapes can also be developed based on maximisation of heat transfer and minimisation of friction factor regarding fluid used in the system.

134 citations