The rapid industrial growth, the population explosion and the pollution of the fresh water reservoirs by industrial wastes have resulted in a large escalation of demand for fresh water. The challenge is harder in the developing countries, where the population growth rate is the highest in the world. Desalination systems are essential to solve this problem, but the conventional desalination solutions are usually technology-intensive devices, most suitable for the energy rich and economically advanced regions of the world. So that, alternative processes like the HDH cycle desalination technologies integrated with renewable energy resources, are more suitable to cover the needs of the poorer countries, specially in case of small-scale applications in rural areas. In literature, the Solar driven HDH desalination process integrated with PVT panels is considered promising, but more studies are needed. In this work, a non-dimensional theory has been set up to create a sizing-methodology valid for the HDH closed-air open-water water-heated (CAOW-WH) cycles in single-stage configuration. A parametric and sensitivity analysis has been produced using the results of the non-dimensional theory. A desalination system driven by PV/T panels, meant to operate in rural areas to satisfy a pure water production rate of 50 kg/h, with a GOR of 1.4 and a RR of 0.7 %, has been consequently designed. Its off-design operation and its response to the optimization of some parameters have been investigated in a wide range of environmental conditions. The developed non-dimensional theory has been also applied with some additional assumptions to the multi-stage configuration, revealing a wide margin of improvement in the performances, which are however thwarted by the problematic technical feasibility of this solution. A comparison between a single-stage and a two-stage configuration at the same total size has revealed that no significant advantages are introduced by the multi-stage configuration, which is moreover penalised by the greater auxiliaries consumptions.
La rapida crescita industriale, l'esplosione demografica e l'inquinamento delle riserve di acqua dolce, causato dagli scarti industriali, hanno prodotto un grande aumento della domanda di acqua dolce. La sfida è più dura nei paesi in via di sviluppo, dove la crescita della popolazione è la più alta del mondo. I sistemi per la dissalazione dell'acqua sono essenziali per risolvere questo problema, ma le soluzioni convenzionali sono di solito costituite da dispositivi molto avanzati tecnologicamente, quindi maggiormente adatti per l'utilizzo nelle regioni più energeticamente ricche ed economicamente avanzate del mondo. Di conseguenza, processi alternativi come le tecnologie basate sui cicli HDH alimentati da energia rinnovabile, sono maggiormente indicati per soddisfare i bisogni dei paesi più poveri, specialmente in caso di applicazioni su piccola scala in aree rurali. In letteratura, la dissalazione tramite ciclo HDH alimentata da energia solare con pannelli PV/T è considerata promettente, ma ulteriori studi di approfondimento sono necessari. In questo lavoro, una teoria adimensionale è stata sviluppata per creare un metodo di dimensionamento valido per i cicli HDH closed-air open-water water-heated (CAOW-WH) in configurazione singolo-stadio. Un'analisi parametrica e di sensitività è stata fatta usando i risultati della teoria adimensionale. Un dissalatore alimentato da pannelli solati PV/T è stato conseguentemente dimensionato per l'utilizzo in aree rurali per soddisfare una produzione di acqua dolce di 50 [kg/h], con un GOR di 1.4 e un RR di 0.7 %. Il funzionamento in condizioni di off-design e la risposta in caso di ottimizzazione di alcuni parametri sono stati investigati per un ampio range di condizioni ambientali. La teoria adimensionale sviluppata è stata anche applicata con delle semplificazioni al caso multi-stadio, rivelando un ampio margine di miglioramento delle prestazioni, tuttavia vanificate dalla problematica fattibilità tecnica della soluzione. Un confronto tra la configurazione singolo-stadio e due-stadi a pari ingombri complessivi ha rivelato che non vengono apportati significativi vantaggi dalla configurazione multi-stadio, la quale in aggiunta è penalizzata da maggiori consumi degli ausiliari.
A new numerical approach for the design of a solar driven humidification-dehumidification desalination process with PV/T modules
MALATTIA, GIORGIO
2018/2019
Abstract
The rapid industrial growth, the population explosion and the pollution of the fresh water reservoirs by industrial wastes have resulted in a large escalation of demand for fresh water. The challenge is harder in the developing countries, where the population growth rate is the highest in the world. Desalination systems are essential to solve this problem, but the conventional desalination solutions are usually technology-intensive devices, most suitable for the energy rich and economically advanced regions of the world. So that, alternative processes like the HDH cycle desalination technologies integrated with renewable energy resources, are more suitable to cover the needs of the poorer countries, specially in case of small-scale applications in rural areas. In literature, the Solar driven HDH desalination process integrated with PVT panels is considered promising, but more studies are needed. In this work, a non-dimensional theory has been set up to create a sizing-methodology valid for the HDH closed-air open-water water-heated (CAOW-WH) cycles in single-stage configuration. A parametric and sensitivity analysis has been produced using the results of the non-dimensional theory. A desalination system driven by PV/T panels, meant to operate in rural areas to satisfy a pure water production rate of 50 kg/h, with a GOR of 1.4 and a RR of 0.7 %, has been consequently designed. Its off-design operation and its response to the optimization of some parameters have been investigated in a wide range of environmental conditions. The developed non-dimensional theory has been also applied with some additional assumptions to the multi-stage configuration, revealing a wide margin of improvement in the performances, which are however thwarted by the problematic technical feasibility of this solution. A comparison between a single-stage and a two-stage configuration at the same total size has revealed that no significant advantages are introduced by the multi-stage configuration, which is moreover penalised by the greater auxiliaries consumptions.| File | Dimensione | Formato | |
|---|---|---|---|
|
MALATTIA_875403_2019.pdf
non accessibile
Dimensione
3.85 MB
Formato
Adobe PDF
|
3.85 MB | Adobe PDF | Visualizza/Apri |
I documenti in POLITesi sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
https://hdl.handle.net/10589/146321