A Novel Humidification Technique Used in Water Desalination Systems Based on the Humidification–Dehumidification Process: Experimentally and Theoretically

The humidification-dehumidification (HDH) desalination technique is a promising technology to harness fresh water, resulting in a decline of scarcities of remote and arid area water. The humidifier unit is one of the major functional elements in an HDH desalination system. The efficiency of any HDH desalination system predominantly depends on the individual humidification and dehumidification process potential. Therefore, improvement in the humidification (or) dehumidification process potential can substantially improve the system’s overall performance. In this work, an attempt has been made to utilize polyvinyl alcohol (PVA) as novel humidifier material for the humidification process. The experimental study was carried out considering diverse inlet air velocities of 3, 2, and 1 m/s. Different cases with and without air preheating were experimented to evaluate the humidification potential of PVA material when utilized in an HDH desalination system powered by waste heat and ambient conditions. The results revealed that the rate of evaporation from PVA material was predominantly influenced by the ambient air temperature compared with other system parameters. Furthermore, comparatively, it was found that, with the use of PVA as humidifier material, average increases in relative humidity of about 19 and 10 % were achieved for higher air velocity of 3 m/s in the cases with and without air preheating, respectively. Thus, it was identified that PVA can be utilized as an effective humidifier material for efficient humidification processes in HDH desalination systems.

Desalination systems based on the Humidification Dehumidification (HDH) process come in a large variety of forms. They all operate in very similar manners, all requiring the evaporation of salt water and the condensation of pure, distilled water, in the same way clouds are formed every day. As engineers we must pursue the processes that have the best possible efficiency for the specific situation we find ourselves in. The purpose of this paper is to explore the various Humidification Dehumidification desalination processes and thermodynamically compare them with one another in order to determine which one of these processes has the most potential in specific environmental situations. This paper explores the advantages and disadvantages of all HDH processes as well as compare them with more common desalination methods like reverse osmosis. An in depth study of available literature is conducted, listed and explained regarding these HDH processes and their specific characteristics, focusing on the key points of efficiency, limiting factors and environmental effects. In some cases these processes, especially those utilizing the open air cycle or solar collectors, can be severely affected by environmental situations. The environmental situations can include high humidity environments, high temperature environments, high rainfall environments and of course the polar opposites of these situations and any combination of them. The paper takes into account these environmental effects and makes recommendations based on different environmental situations that can be found around the world. The HDH processes can obtain the energy they need to operate from various sources. Recommendations are also made with this in mind. Recommendations are also made regarding possible processes and specific design areas, which, in the in the writers opinion, should be the focus of improvements made by future designers are noted. Considering the efficiency limiting areas that cause bottlenecks in the processes, the writer prescribes possible ways to limit the effects of these bottleneck areas. The writer’s own recommendations regarding possible processes and possible improvements are also stated, paying attention to the recommendations already found in literature.

Thermodynamic study on an enhanced humidification-dehumidification solar desalination system with weakly compressed air and internal heat recovery

Parameter analysis and optimization of a two-stage solar assisted heat pump desalination system based on humidification-dehumidification process

Ultrasonic atomization technique for enhancing humidification process in thermal desalination

Performance of a two-stage multi-effect desalination system based on humidification–dehumidification process

A study of the performance enhancement of a humidification-dehumidification (HDH) system integrated with multiple evaporators/condensers heat pump (HP) and heat recovery units is presented. The HP unit is intended to deliver necessary heating for humidifier and heating/cooling for dehumidifier in a new strategy. The proposed integrated system is capable to produce fresh water from the HDH system and HP unit. Four different configurations of the system formed by excluding/adding condensers and evaporators were investigated; mode-A (seawater precooling and reheating), mode-B (seawater reheating), mode-C (seawater precooling and humid air reheating), and mode-D (humid air reheating). Fresh water productivity, fresh water ratio, system water recovery, gain output ratio, specific work consumption, and fresh water production cost were used as performance measuring parameters of the system. The influences of operating parameters on the system performance were analytically studied and experimentally validated for different system configurations. The results indicate the enhancement of the systems' performance with increasing ambient air temperature and humidity, seawater and air flow rates, and with decreasing seawater temperature. The system configuration of mode-B shows the best performance with fresh water production of 61.94 kg/h and gain output ratio of 4.97 which are higher than those of the other configurations by 13%, 55%, 85% and 11%, 48%, and 75%, respectively. Comparisons of the proposed configurations with the other HDH desalination systems available in the literature were presented and better performance of the proposed systems was noticed.

ILASS 2017 is the 28th European Conference on Liquid Atomization and Spray Systems. Following the successful 26th ILASS 2014 (Bremen) and 27 th ILASS 2016 conferences, we will continue this tradition by providing a venue for industrial and academic researchers and students to engage in the scientific development and practice of Atomization and Spray Systems and to meet and share recent developments in these fields. ILASS is the Institute for liquid atomization and spray systems . ILASS Europe has its roots in an initiative of the late Paul Eisenklam, who established the institute in 1982.

Air humidity significantly affects the sound of wooden instruments. The sound quality decreases when the instrument is exposed to low humidity for an extended period. Therefore, the instrument is treated with a humidifier to improve sound quality. This study aimed to verify the effectiveness of the humidification process by analyzing the quality of guitar sound with the methods used in signal complexity studies, such as Higuchi’s fractal dimension (HFD), symbolic analysis, and empirical mode decomposition (EMD). The sound quality was determined by the sound levels measured before, during, and after the guitars’ humidification. The methods used consistently confirmed the improvement of the guitar sound quality after the humidification process. Moreover, it was concluded that the sound quality changes irregularly during the humidification process.

Pericarp browning is the major cause of deterioration of harvested litchi fruit. Water loss plays a role in pericarp browning of litchi fruit. This study investigated the effects of humidification with dry fog on pericarp browning and quality of litchi fruit stored at low temperature. Litchi fruit were stored in a non-humidified cold chamber (control) or in a humidified cold room using Tabor atomizer system that generated 95% relative humidity (RH) without depositing water on the fruit surface at 4°C. Control fruit stored in cold room without added humidity underwent rapid weight loss, accompanied by severe pericarp browning after 25 d of storage. However, slight weight loss and no obvious pericarp browning were found in humidified-fruit. Moreover, humidification maintained well the integrity of cell membrane and inhibited polyphenol oxidase activity during early storage. In addition, respiration rate was obviously inhibited in humidified-fruit compared with control fruit. This study might provide a convenient approach to reduce pericarp browning of harvested litchi fruit by humidifying the fruit using the Tabor atomizer at low temperature instead of packaging with film. Keywords: litchi, pericarp browning, dry fog, high relative humidity, cold storage DOI: 10.25165/j.ijabe.20191204.4420 Citation: Xiao L, Li T T, Jiang G X, John A, Zhang D D, Jin W Y, et al. Effects of dry fog humidification on pericarp browning and quality of litchi fruit stored at low temperature. Int J Agric & Biol Eng, 2019; 12(4): 192–196.

Technical improvements and perspectives on humidification-dehumidification desalination — A review

Water productivity enhancement in variable pressure humidification dehumidification (HDH) desalination systems using heat pump

Humidification–dehumidification desalination system driven by geothermal energy

Japanese symposium on liquid atomization and spray systems has been successfully held once a year since 1972, with the purpose of the interchange between researchers and engineers in many fields of atomization. Such activity in Japan gave the hopeful impact to other countries, made the opportunity of international exchange, and the first conference was held at Tokyo in 1978.Papers submitted to the domestic seventeen symposiums and the four international conferences covers the wide ranges of studies on liquid atomization correspondind to the developing of industrial techniques. Liquid break-up mechanisms are fully investigated on liquid columns and films, liquid droplets, and liquid jets injected from various nozzles. Many reports on the improvement of atomizers and spray characteristics are presented every time, especially on twin-fluid atomization, and ultra-sonic atomization was concentricly reported in 1985. Atomization of coal-water slurry and flashing atomization were also appeared at the third international conference.Real-time laser measurements of spray based on various optical principles have been brilliantly proposed since 1985. They are very useful for the clarification of liquid disintegration and spray transport phenomena, but have several ploblems to be solved concerning spatial spray dennsity, data management and explanation of spray informations.

Solar desalination based on humidification process—I. Evaluating the heat and mass transfer coefficients