Dehumidification Research Articles

On the importance of the heat and mass transfer driving force reversal and heat-cold offset in internally-cooled liquid-desiccant system

The internally-cooled liquid-desiccant (ICLD) air-conditioning system has gained more attention, owing to its energy-efficient performance. In this study, two restriction factors of the conventional heat-pump driven ICLD system are revealed: (i) heat and mass transfer driving force reversal phenomena exist in the dehumidifier (DEH) and regenerator (REG), which deteriorate the moisture efficiencies of the DEH and REG; (ii) considerable heat-cold offset occurs during solution exchanging between the DEH and REG. To avoid the driving force reversal phenomena, the system I with a pre-cooler/heater before the DEH/REG is proposed. The COPsys of the system I is 8.2%–15.0% greater than that of the conventional ICLD system, under variable conditions. To reduce the heat-cold offset to further improve the system performance, the system II is then proposed. In the proposed system II, 20% of the original DEH/REG is changed from the original internally-cooled type into the adiabatic type. The hybrid DEH and REG help to reduce the temperature difference between the outlet solutions of the DEH and REG, and thus, the heat-cold offset in the system is reduced. Consequently, COPsys of the proposed system II is 11.0%–19.5% greater than that of the conventional system, under variable conditions.

Investigation on heat and mass transfer characteristics for a zeolite-coated heat exchanger using comparatively low-temperature energy: Heating humidification mode and cooling dehumidification mode:

Desiccant-based hybrid air-conditioning technologies are currently being developed to reduce energy consumption and enhance the effectiveness of indoor thermal environmental control in buildings. T...

Design and Fabrication of a Dehumidifier with a Heating Module for Greenhouses

Design and Fabrication of a Dehumidifier with a Heating Module for Greenhouses

Clinical effect of minimally invasive painless Carisolv iodide removal technique in the treatment of dental caries

Objective To investigate the clinical effect of minimally invasive painless iodide removal technique in the treatment of dental caries. Methods From January 2017 to October 2017, 60 patients with dental caries in Xiaogang Hospital of Beilun District were selected and divided into observation group(n=50)and control group(n=50). The patients in the control group were treated by traditional dental drill dehumidification technique, and the patients in the observation group were treated by minimally invasive painless iodide removal technique.The clinical effects of the two groups were compared and analyzed. Results The total effective rate, the severe pain during treatment and the slight pain sensation of the observation group were 94%, 0%, 14%, respectively, which were better than those of the control group(72%, 10%, 46%), the differences between the two groups were statistically significant(χ2=11.254, 5.011, 9.451, all P<0.05). Conclusion The use of Carisolv iodine can reduce the use of anesthetic, or reduce the necessity of using the needle, which can reduce the pain and discomfort of the patients.There is a choice to remove caries, will not damage the normal dental tissue, can reduce the occurrence of complications, which can prolong the life of teeth and reduce the probability of infection, thus to prevent tissue around the tooth from being damaged. Key words: Dental caries; Dental prosthesis repair; Iodine compounds

A Study on the Use of Additional Sound to Compensate the Defects of the Dehumidifier

A Study on the Use of Additional Sound to Compensate the Defects of the Dehumidifier

Application of Evaporative Air Coolers Coupled With Solar Water Heater for Dehumidification of Indoor Air

Application of Evaporative Air Coolers Coupled With Solar Water Heater for Dehumidification of Indoor Air

Exergy analysis of a liquid desiccant evaporative cooling system

In this paper, a model of liquid desiccant evaporative cooling system is presented and simulated. The objective of this paper is to reveal the effects of various parameters on thermodynamic performance and to show the optimal range of those parameters. These results show that the system performance is strongly influenced by the hot water temperature, the flow ratio of air to solution and ambient air relative humidity, followed by the hot water flow rate. And the optimal range of each influencing factor is determined as follows: hot water temperature and the value of ma/ms are adopted to be about 75 °C and 1 kg⋅kg−1 respectively, while hot water flow rate will not be greater than 0.6 kg⋅s−1 and the range of the relative humidity of the atmosphere is wide. The analysis of the exergy efficiency ratio shows that the regenerator (REG), dehumidifier (DEH) and the enthalpy exchanger (EX) in the system are the weak parts of the system.

Death Related to the Dehumidifying Agent

Death Related to the Dehumidifying Agent

1C4-3 A study on the dehumidifier in consideration of the Korean living environment

1C4-3 A study on the dehumidifier in consideration of the Korean living environment

State-of-the-art in liquid-to-air membrane energy exchangers (LAMEEs): A comprehensive review

Abstract Buildings are responsible for a significant portion of the global energy consumption. In particular, heating, ventilation, and air-conditioning (HVAC) systems in buildings consume significant amounts of energy. Liquid desiccant dehumidification and energy recovery are effective energy conservation technologies in HVAC systems. Direct-contact liquid desiccant air-conditioning systems have the risk of carry-over of aerosol droplets to the supply airstream, which may cause health problems for occupants and corrosion of the ducting system. Liquid-to-air membrane energy exchanger (LAMEE) is a novel semi-permeable membrane-based liquid desiccant energy exchanger, which transfer heat and moisture simultaneously but can eliminate the desiccant solution aerosol carry-over problem. Two LAMEEs can also be used to constitute a run-around membrane energy exchanger (RAMEE) system to recover heat and moisture from exhaust air in buildings. In the past decade, research and development of LAMEEs has been very active to show that high effectiveness is possible. This paper presents a comprehensive review of the design and performance of LAMEEs.

Analysis and laboratory tests to evaluate the composition and the behaviour of some dehumidifying mortars used in the restoration field

The aim of this work is to study some commercial products, defined dehumidifying mortars, in order to verify their composition and their performance characteristics in comparison with the technical specifications supplied by the industries. In fact, the real composition and the properties of the commercial products often differ from those declared by the suppliers. In the field of conservation the commercial products are widely used and the restorers choose the most appropriate one also on the base of the declared characteristics. So it is of particular relevance in conservation and restoration applications to know the real composition and the performance characteristics of a commercial product. Starting from these general remarks, 20 commercial products were examined, in collaboration with the Society Mapei, in order to verify their composition and their physical-mechanical characteristics. The analyses of the mortars were carried out in the Laboratory of Diagnostics for Conservation and Restoration of University of Tuscia and in the Mapei’s research laboratories in Milano. The analyses and tests were performed on the products and on the specimens prepared according to the specifications referred in the technical data sheets supplied together with the mortars. In particular, the following analyses were undertaken: 1) Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), X-ray diffraction (XRD), thermo gravimetric (TG) and differential scanning calorimetry (DSC), and Fourier Transform Infrared spectroscopy (FT-IR) in the Mapei’s laboratories, and 2) granulometry analysis, colour measurements, pH and conductance measurements, FT-IR spectroscopy, in the laboratories of University of Tuscia. Moreover, some specific tests were carried out to study the mechanical and physical-chemical properties of the specimens: capillarity water absorption (UNI 10859: 2000), water absorption due to total immersion (imbibition capability, NORMAL 7/81), drying index measurement (NORMAL 29/88), and micro drilling tests. The results of this study indicate that the examined dehumidifying mortars not always respect the requisites required to a product to be used in the restoration of historical buildings. This suggests the necessity to verify the composition and the characteristics of the commercial products used in the conservation applications in order to choose the most appropriate materials and procedure to guarantee the safeguard of the historical buildings.

ENHANCEMENT OF THE PROCESSES OF DESICCANT AIR CONDITIONING SYSTEM

An experimental study was carried out to evaluate t he liquid desiccant system performance during dehum idification and humidification processes using air injection throug h the liquid desiccant solution (Calcium Chloride). The air flows cross the desiccant solution with different air mass flow rat es. The system is studied at different operating co ndition (air flow rate, temperature, humidity ratio and solution levels). The effectiven ess of the proposed system for both dehumidificatio n and humidification processes were evaluated. Also, the cooling effect and mass tcoefficient was obtained. It is found that the system effectiveness reached 0.75 in the dehumidification process and 0.7 in the humidification process. Mass transfer coefficient depends on the air mass flow rate and the desiccant solution level in the tank Econom ical Results of the presented system is estimated

Study on the Heat Transfer of the Rectangular Fin with Dehumidification: Temperature Distribution and Fin Efficiency

This study presents a numerical investigation of the fin efficiency and temperature distribution of a plain fin with combined heat and mass transfer. Using the finite difference scheme the differential equation results from an energy balance on an element of the fin has been solved to obtain temperature distribution along the fin surface. The effects of variations in relative humidity, dry air and fin base temperatures, atmospheric pressure, and fin pitch on temperature distribution and also on fin efficiency are discussed.

Modeling of convective drying of safed musli (Chlorophytum borivilinum).

The drying kinetics of Safed musli (Chlorophytum borivilinum) in terms of moisture content, moisture ratio, drying time and drying rate was investigated. A laboratory model dehumidified air dryer and a hot air dryer (Tray dryer) were employed to study the drying behavior at 30, 35, 40 and 45°C. Safed musli drying primarily occurred in falling rate period. The drying data were fitted to seven thin layer drying models and the two-term model satisfactorily described the drying behavior of safed musli roots with highest coefficient of determination (R2) and lowest chi-square (c2), root mean square error (RMSE) and mean bias error (MBE) values except at 30°C in dehumidified air dryer where logarithmic model was found as the best model having the highest R2 and lowest c2, RMSE and MBE values. Effective moisture diffusivity (Deff) of safed musli was found to increase with the increase in drying air temperature and it ranged from 2.23010 × 10-7 to 4.43057 × 10-7 m2/s. The results of the study are very useful for commercial scale drying of safed musli to optimize drying process and to achieve superior quality of dried product. Key words: Drying, dehumidified air dryer, tray dryer, safed musli, modeling.

Experimental study on optimizing cheese drying and ripening process

The system proposed in this paper consists of humidity and temperature control during the food maturation process by using a dehumidifier equipped with a desiccant rotor containing silica gel. In this system the condensation/drainage stage is omitted since the humid room air is directed out of the cold store (process air) and the dried air is introduced via the dehumidifier inside the cold store. It allows separate control of the humidity and temperature inside the cold store. The experimental results are obtained in real conditions; the weight loss of the products was determined and it was, also, proved that dried products such as cheeses treated by this method retain their fresh color, texture and other organoleptic properties to ensure their final quality.

Dehumidifying Drying of Dehydrated Radish in Greenhouse (I)

Dehumidifying Drying of Dehydrated Radish in Greenhouse (I)

The analysis of humidity factor in cestamide materials on surface roughness with the help of artificial neural network

Cestamide, an engineering plastic, is used in many areas of industry today. Apart from its excellent mechanic features; it also has a negative feature, namely dehumidification. It is necessary to detect cutting conditions of dehumidified cestamide materials for metal cutting. After the process of humid and dry cestamides under same cutting conditions, the change of average surface roughness quality is studied by performing some experiments. For this, after keeping materials in humid and dry environment, cestamide materials are processed with same kind of cutting tool in (1, 1.5, 2, 2.5, 3 mm) chip thickness (ap), (90, 110, 130 m/min) cutting speed (Vc) (100, 120, 140,160 mm/min) feed rate (f) and then average difference of surface roughness values are detected. Moreover, an Artificial Neural Network (ANN) modelling is developed with the results obtained from the experiments. For the training of ANN model; material type, cutting speed, cutting rate and depth of cut parameters are used. In this way, average surface roughness values except for the mentioned experiment could be estimated. Experimental results and ANN model results show that, different average surface roughness values are obtained for applying same processing conditions humidity factor on cestamide materials. It is observed that a case which is based on different variables such as average surface roughness can be estimated in acceptable error rate with the help of ANN model. Key words: Artificial neural network (ANN), cestamide materials, average surface roughness.

Dehumidification and regeneration efficiency of the mixed salt solution in the solar dehumidification system

Dehumidification and regeneration efficiency of the mixed salt solution in the solar dehumidification system

Indoor Climate Design for a Monumental Building with Periodic High Indoor Moisture Loads / Planung des Raumklimas eines Baudenkmals mit hoher periodischer Feuchtigkeitsbelastung

Article Indoor Climate Design for a Monumental Building with Periodic High Indoor Moisture Loads / Planung des Raumklimas eines Baudenkmals mit hoher periodischer Feuchtigkeitsbelastung was published on February 1, 2008 in the journal Restoration of Buildings and Monuments (volume 14, issue 1).

Treatment of a Specialty Paper Mill Wastewater Using a Pilot-scale Pulsed Electrocoagulation Unit

We used a pilot-scale pulsed electrocoagulation (EC) system capable of treating 0.5~1m^3 h^(-1), with a hydraulic retention time (HRT) of 2.17~6.5 min, and consisting of a homogenizer tank, a pulsed EC reactor, an aerator, a flocculation tank, and a sedimentation tank to treat specialty paper mill wastewater from central Taiwan. The mill has a daily production of 5 t d^(-1), and discharges 1300m^3 d^(-1) of wastewater. It produces mainly filter papers for air conditioners and dehumidifiers, medical industrial paper, home decoration paper, special wrapping and packaging papers, and other specialty papers. A wastewater stream from making black-colored specialty paper was treated in this study. The wastewater was pumped to a 1-m^3 homogenizing tank to even out fluctuations in water quality before entering the treatment unit. The controlled parameters of the pulsed EC unit included the use of either iron or aluminum electrodes, current density, and HRT (flow rate). The wastewater quality variables examined before and after the treatment include electrical conductivity, suspended solids (SS), chemical oxygen demand (COD), and true color. The results indicated that electrical conductivity decreased with increasing current density and HRT; under all current densities, SS removal appeared to have no correlation with the flow rate, and a minimum of 85% SS removal was observed. Removal of COD was dependent on the electrode materials. When iron electrodes were used, due to the low COD of the original wastewater, the post-treatment effluent tended to have large amounts of ferric ions which interfered with the COD measurements. Aluminum electrodes, on the other hand, achieved at least a 40% COD removal at lower current densities. With both electrodes, the higher the current density and the longer the HRT, the greater the true color removal rates became. Under the best operational conditions (a current density of 106.7Am^(-2), and an HRT of 3.25 min) using aluminum electrodes achieved removals of 25.4, 97.14, 76.47 and 70.09% of electrical conductivity, SS, COD, and true color, respectively. The current dissolved air flotation unit costs NT$2.68 (US$0.0812) per ton of wastewater to operate, while the pulsed EC unit costs NT$2.42 (US$0.0733) per ton of wastewater. A proposed 5-stage mechanism of the EC system is also discussed.