On site experimental evaluation of a low-temperature solar organic Rankine cycle system for RO desalination

Manolakos, D.E.; Kosmadakis, George; Kyritsis, S.; Papadakis, G.

doi:10.1016/j.solener.2008.10.014

Cited by 142 publications

(41 citation statements)

References 9 publications

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“…To date, though several design studies [9][10][11] have indicated that the performance of such Rankine-RO systems should be comparable with those of photovoltaic-RO systems, practical experience has shown rather lower efficiencies [12,13]. The batch system is expected to give significant improvements, but one factor that could compromise its performance is the longitudinal dispersion in the RO module.…”

Section: Introductionmentioning

confidence: 99%

Longitudinal dispersion in spiral wound RO modules and its effect on the performance of batch mode RO operations

Qiu

Davies

2012

Desalination

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Operation of reverse osmosis (RO) in cyclic batch mode can in principle provide both high energy efficiency and high recovery. However, one factor that causes the performance to be less than ideal is longitudinal dispersion in the RO module. At the end of the batch pressurisation phase it is necessary to purge and then refill the module. During the purge and refill phases, dispersion causes undesirable mixing of concentrated brine with less concentrated feed water, therefore increasing the salt concentration and energy usage in the subsequent pressurisation phase of the cycle. In this study, we quantify the significance of dispersion through theory and experiment. We provide an analysis that relates the energy efficiency of the batch operation to the amount of dispersion. With the help of a model based on the analysis by Taylor, dispersion is quantified according to flow rate. The model is confirmed by experiments with two types of proprietary spiral wound RO modules, using sodium chloride (NaCl) solutions of concentration 1000 to 20,000 ppm. In practice the typical energy usage increases by 4 to 5.5% compared to the ideal case of zero dispersion.

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Section: Introductionmentioning

confidence: 99%

Longitudinal dispersion in spiral wound RO modules and its effect on the performance of batch mode RO operations

Qiu

Davies

2012

Desalination

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“…Most of them use conventional solar collectors (either flat type or with evacuated tube ones) or collectors with reflectors (such as parabolic troughs), for conversion of the incident solar radiation to usable heat [6,7]. Recently, an alternative configuration has been developed and tested, which is based on concentrating PV/thermal collectors, which produce both heat and electricity.…”

Section: Research On Solar Orc Unitsmentioning

confidence: 99%

“…The main advantage at this low temperature range is the simple and low-cost heat source circuit and simple ORC configuration [2,3] (i.e. single expansion machine and no internal heat exchangers).There are numerous studies especially for solar thermal energy applications, proving the importance, flexibility and potential costeffectiveness of such energy systems [4][5][6][7][8]. Most of them focus on the power production from the ORC part, which is then converted to electricity, with the aim to maximize net power production.…”

mentioning

confidence: 99%

Developments on Small-Scale Organic Rankine Cycle (ORC) Systems

Kosmadakis¹,

Manolakos²,

Papadakis

2016

J Fundam Renewable Energy Appl

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EditorialThe organic Rankine cycle (ORC) technology is perhaps the most suitable technology for heat recovery applications from sources of low temperature (even lower than 100°C) [1], while it can also be used for temperatures up to about 300°C with a variety of scale (from the kW up to the MW scale). At low temperatures its efficiency is usually in the range of 4-6 %, but still there are cases where it can be cost effective, especially for waste heat recovery thus improving the overall process/ system energy efficiency. The main advantage at this low temperature range is the simple and low-cost heat source circuit and simple ORC configuration [2,3] (i.e. single expansion machine and no internal heat exchangers).There are numerous studies especially for solar thermal energy applications, proving the importance, flexibility and potential costeffectiveness of such energy systems [4][5][6][7][8]. Most of them focus on the power production from the ORC part, which is then converted to electricity, with the aim to maximize net power production. Some priority aspects of the researchers dealing with such systems is the design of the ORC [2], the organic fluid selection [9,10], the control and possible thermal storage unit [11], and the appropriate expansion machine [12][13][14]. The Renewable Energy Systems Group (RES Group) at the Agricultural University of Athens (AUA), (www.renewables.aua.gr) focuses on two major issues relevant to ORC technology, which are mentioned next:1. Optimization of solar conversion to electricity through advanced design and control. 2. Development of unique expanders, included in a variety of ORC units (for different applications). Research on Solar ORC UnitsVarious solar ORC units have been developed in the past. Most of them use conventional solar collectors (either flat type or with evacuated tube ones) or collectors with reflectors (such as parabolic troughs), for conversion of the incident solar radiation to usable heat [6,7]. Recently, an alternative configuration has been developed and tested, which is based on concentrating PV/thermal collectors, which produce both heat and electricity. The key parameter of the hybrid concentrating photovoltaic/thermal (CPV/T) system design is the temperature of the heat transfer fluid, transferring heat from the CPV/T to the ORC unit, through the evaporator, having a major effect on the performance of both the PV cells and the ORC engine. The motivation is the utilization of solar thermal energy from the CPV/T by an ORC unit for producing additional electricity. By doing so, the total electricity production of such hybrid systems can be significantly increased, contributing also to the increase of their flexibility. Finally, such system can also operate at CHP mode, which is currently being examined. This system has a combined capacity of 13 kW (10 from PV part and 3 kW from ORC part) and has been tested at AUA field with promising results in the framework of a EU-funded project (CPV/ Rankine: www.cpvrankine.aua.gr). The ORC housing and a part of t...

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“…Manolakos et al conducted an experimental study to investigate the performance of a solar ORC employing HFC134a for reverse osmosis desalination [5][6][7]. A solar ORC considering FPC and ETC was investigated in [8].…”

Section: Introductionmentioning

confidence: 99%

A Theoretical and Experimental Study of HFE-7000 in a Small Scale Solar Organic Rankine Cycle As a Thermofluid

Helvaci

Khan

2017

Volume 2: I&C, Digital Controls, and Influence of Human Factors; Plant Construction Issues and Supply Chain Management; Pla

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Renewable energy technologies and sources have been playing a key role in reducing reliance on fossil fuels and significantly reducing CO 2 emissions and its footprint. EU initiative of generating 50% of the energy needs through sustainable sources by 2050 needs a direct response in terms of providing applied solutions to realize this target on time. Solar energy is one of the major and abundantly renewable energy sources which are free and clean. Solar energy can be utilized by means of solar Photovoltaic (PV) or solar collectors. Concentrating solar collectors supply thermal energy from medium to high grade where as non-concentrating collectors (flat plate) delivers low-grade thermal energy. The use of thermofluids with boiling temperatures lower than the water, allows the operation of low grade solar thermal systems on an Organic Rankine Cycle (ORC) to generate both mechanical and heat energy. At the same time, the selection of appropriate thermofluid is an important process and has a significant effect both on the system performance and the environment. Conventional thermofluids such as Chlorofluorocarbons (CFCs) and Hydrochlorofluorocarbons (HCFCs) have high ozone depletion (ODP) and high global warming (GWP) potential. It is therefore important to investigate novel and environmentally friendly thermofluids to address environmental impacts as global warming and ozone layer depletion. Hydrofluoroethers (HFEs) are non-ozone depleting substances and they have relatively low GWP. Therefore, HFEs can be used as a replacement for CFCs and HCFCs. In this study, a solar ORC is designed and commissioned to use HFE 7000 as a thermofluid. The proposed system consists of a flat-plate solar collector, a vane expander, a condenser and a pump where the collector and the expander are used as the heat source and prime mover of the cycle respectively. The performance of the system is determined through energy analysis. Then, a mathematical model of the cycle is developed to perform the simulations using HFE-7000 at various expander pressure. Experimental data indicated that the efficiency and the net mechanical work output of the cycle was found to be 3.81% and 135.96 W respectively. The simulation results showed that increasing the pressure ratio of the cycle decreased the amount of the heat that is transferred to HFE 7000 in the collector due to the increased heat loss from the collector to the environment. Furthermore, net output of the system followed a linear augmentation as the pressure ratio of the system increased. In conclusion, both the experimental and theoretical research indicates that HFE 7000 offers a viable alternative to be used efficiently in small scale solar ORCs to generate mechanical and heat energy.

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On site experimental evaluation of a low-temperature solar organic Rankine cycle system for RO desalination

Cited by 142 publications

References 9 publications

Longitudinal dispersion in spiral wound RO modules and its effect on the performance of batch mode RO operations

Longitudinal dispersion in spiral wound RO modules and its effect on the performance of batch mode RO operations

Developments on Small-Scale Organic Rankine Cycle (ORC) Systems

A Theoretical and Experimental Study of HFE-7000 in a Small Scale Solar Organic Rankine Cycle As a Thermofluid

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