Search results for " heat recovery"

Reverse electrodialysis heat-engine: Case studies of improving energy efficiency through recovery of low temperature excess heat

2018

Reverse Electrodialysis (RED) is a technology for generating electricity from the difference in salinity between two solutions. RED is usually applied to natural water streams with different salinities, like seawater vs. freshwater. In the RED Heat-to-Power project we explore the option of using artificial water solutions operating in a closed loop where the difference in salinity is regenerated in a separation step powered by heat at temperature ranges between 60 and 100°C. We call this system Reverse Electrodialysis Heat Engine (RED HE). In this paper, first we summarise the possible system configurations and the overall amount of excess heat available in Europe for powering the RED HE pr…

Concepts for medium-high to high temperature thermoelectric heat-to-electricity conversion: a review of selected materials and basic considerations o…

2015

Within the last decade, novel materials concepts and nanotechnology have resulted in a great increase of the conversion efficiency of thermoelectric materials. Despite this, a mass market for thermoelectric heat-to-electricity conversion is yet to be opened up. One reason for this is that the transfer of the lab records into fabrication techniques which enable thermoelectric generator modules is very challenging. By closing the gap between record lab values and modules, broad industrial applications may become feasible. In this review, we compare three classes of materials, all designed for medium-high to high temperature applications in the field of waste heat recovery: skutterudites, half…

The first operating thermolytic reverse electrodialysis heat engine

2020

Abstract Thermolytic reverse electrodialysis heat engine (t-RED HE) has been recently proposed as a technology for converting low-temperature waste heat into electricity. The construction and operation of the first world lab-scale prototype unit are reported. The system consists of: (i) a reverse electrodialysis unit where, the concentration gradient between two solutions of thermolytic salts is converted into electricity and (ii) a thermally-driven regeneration unit where low-temperature heat is used to restore the initial conditions of the two feed streams. Regeneration is based on a degradation process of salts into gaseous ammonia and carbon dioxide, which can be removed almost entirely…

Methods for Enhancing the Thermal Durability of High-Temperature Thermoelectric Materials

2013

Author's version of an article in the journal: Journal of Electronic Materials. Also available from the publisher at: http://dx.doi.org/10.1007/s11664-013-2917-0 Thermoelectric materials, for example skutterudites and magnesium silicides, are being investigated as promising materials for medium-to-high-temperature waste heat recovery in transport and in industry. A crucial aspect of the success of a thermoelectric material is its stability over time when exposed to rapid heating and cooling. In this work different aspects of the degradation of these thermoelectric materials at high temperature were examined. Initial thermal durability was studied, and several candidate coatings were evaluat…

OPTIMIZATION OF COGENERATION PLANT FOR APPLICATIONS IN FOOD INDUSTRY

2013

Cogeneration systems represent an effective solution for optimizing energy performance of users with contemporary thermal and electrical energy demand. An energy audit of an industrial pasta factory equipped with a cogeneration system natural gas fuelled has carried out along last two years. This CHP plant, with a 650 kWe capacity, currently covers a relevant fraction of the electric and high-temperature heat loads during peak hours, while it is switched off during off-peak hours because of the much lower electricity price. Heat content of flue gases is recovered by two cascaded gas-diathermic oil and diathermic oil- water heat exchangers; the superheated water obtained is then supplied to …

Supertargeting-based hierarchic evaluation for setting paths in relaxation of retrofitted Heat Exchanger Networks

2010

The application of pinch analysis to the retrofit of existing heat exchanger networks is a complex task, which can be hardly standardised due to the large number of unquantifiable design considerations. Top-down and bottom-up approaches have been usually pursued, respectively oriented to relax a Maximum Energy Recovery (MER) configuration and to improve the existing network by removing network pinches. In this paper the bottom-up approach is critically examined, considering a well known case study represented by an aromatics plant; a MER design is also obtained and evaluated, to represent a target for process improvement. The final objective of researches in this sector is the identificatio…

Organic Rankine Cycle fed by flat-plate solar collectors: a case study

2015

L'attuale tendenza dell’utilizzo di sistemi di risorse energetiche distribuite (sistemi DER), insieme con il crescente sviluppo tecnologico, incoraggia l'uso di tecnologie capaci di recuperare efficacemente energia da fonti di calore a temperatura bassa o moderata, che rappresentano un'opzione essenziale per affrontare le problematiche energetiche ed ambientali. In questo contesto, i cicli Rankine a fluido organico (ORC) si stanno affermando come una tecnologia molto promettente tra quelle attualmente disponibili, in particolare per bassi valori di temperatura. I principi di funzionamento dei sistemi ORC sono essenzialmente gli stessi di quelli del ciclo Rankine. Nei sistemi ORC, l’acqua è …

Combined membrane and thermal desalination processes for the treatment of ion exchange resins spent brine

2019

Abstract The disposal of industrial wastewater effluents represents a critical environmental issue. This work focuses on the treatment of the spent brine produced by the regeneration of ion exchange resins employed for water softening. For the first time, a comprehensive techno-economic assessment and an analysis of the energy requirements of the treatment chain are carried out, via the simulation of ad hoc implemented models. The chain is composed of nanofiltration, double-stage crystallization and multi-effect distillation. The valuable product is the brine produced by the multi-effect distillation, which can be re-used for the regeneration. Therefore, the treatment chain’s economic feasi…

REVERSE ELECTRODIALYSIS HEAT ENGINE: Low-grade Waste Heat into Electricity

Our society is undergoing a progressive change about the life style and habits. The world population is continuously increasing with 7.6 billion of human beings in 2018, resulting in an increasingly demand of resources in terms of food, water and energy. The exploitation of the planet resources since the first Industrial Revolution, results today in an unsustainable condition, which requires fundamental changes. In particular, in the energy sector the adoption of fossil fuels as the main energy source for human beings’ activities resulted in a strong impact on our planet, leading to climate changes and environmental pollution. Nowadays these aspects have induced society to a substantial cha…

Reverse electrodialysis with NH4HCO3-water systems for heat-to-power conversion

2017

Abstract A Reverse ElectroDialysis Heat Engine (REDHE) system operating with “thermolytic” ammonium hydrogen-carbonate (NH4HCO3) aqueous solutions as working fluids is studied. The engine is constituted by (i) a RED unit to produce electric power by mixing the solutions at different salinity and (ii) a thermally-driven regeneration unit including a stripping and an absorption column to restore the initial salinity gradient thus closing the cycle. In the present work only the RED unit and the stripping column are taken into account. In particular, a simplified integrated process model for the whole cycle was developed: it consists of (i) a lumped parameter model for the RED unit validated wi…