WO2022013748A1

WO2022013748A1 - A humidifier-dehumidifier based fluid treatment system

Info

Publication number: WO2022013748A1
Application number: PCT/IB2021/056305
Authority: WO
Inventors: Prakash Bhalekar; Anirudh Bhalekar
Original assignee: Padmini Vna Mechatronics Pvt. Ltd.; Quadsun Solar Private Limited
Priority date: 2020-07-13
Filing date: 2021-07-13
Publication date: 2022-01-20

Abstract

The present invention relates to a humidifier-dehumidifier based fluid treatment system comprising of a closed housing (11), evaporator unit (12), condenser unit (13), plurality of fan (14), air/gas inlet (15) and liquid transmission lines (16), wherein, said evaporator unit (12) utilizes renewable energy to heat said fluid/ effluent for evaporation and under an intelligent control of air flow the evaporation rate is maximized, said evaporator unit (12) and condenser unit (13) are installed in said closed housing (11) to form a closed loop for reducing energy consumption, said heating apparatus (18) comprises of a low lift heat pump (27) and a temperature management unit (28), said humidifier- dehumidifier based fluid treatment system (10) includes at least two humidity sensors (24) connected with ground, data and live wires and utilizes a control unit to intelligently control the induction of fresh air and outlet of humid air to manage the air psychometrics.

Description

“A HUMIDIFIER-DEHUMTOIFIER BASED FLUID TREATMENT

SYSTEM”

FIELD OF THE INVENTION

The present invention relates to a humidifier-dehumidifier based fluid treatment system. More particularly, the present invention relates to a humidifier-dehumidifier based fluid treatment system used for distilling pure water out of impure water. The fluid treatment system has application in distilling any other pure liquid from dissolved impurities.

BACKGROUND OF THE INVENTION

Treatment of fluids had always been a topic of research ever since the harmful effects of use of contaminated liquid are exposed. The harmful effects related to consumption of impure water are one aspect that motivates on developing new technology for purification of water. The other aspect that motivates towards development of new technology for fluid treatment is that a lot of fluids used for industrial purpose, if contaminated adversely affect the operation and performance.

In addition, the effluents released in natural water bodies require treatment as they largely affect the environment. Some commonly used methods for effluent treatment include neutralization cum equalization, chemical coagulation, settling treatment, chemical coagulation and precipitation and biological treatment etc. One more concern that increases the importance of fluid treatment is that a lot of water bodies are found in nature which may be turned useful for human after it is treated and made fit for human use. Some of the natural water bodies are saline and hence desalination of this water makes it fit for human use.

One commonly used technique for fluid treatment is humidification and dehumidification of fluid which separates the pure liquid from the dissolved impurities. In this technique, while humidification, the contaminated fluid is made to evaporate using an air flow as humid air and leaving behind the dissolved impurities and while dehumidification, the humid air is condensed to obtain a pure fluid. Hence, this combination of humidification and dehumidification is useful in obtaining a pure fluid. However, there are some drawbacks of this technique such as need of controlled flow of liquid and air, timely emptying and filling of the reservoirs attached for providing fluid for evaporation and storing the condensed liquid. Also, on industrial level such systems have a large power consumption.

US3740959A teaches a humidifier-dehumidifier device that operates in combination with a water closet. The device includes a housing with a fan mounted therein. The fan blows air through water transfer means and cooling fins positioned within the housing. Control means alteratively energize the water transfer means to humidify the air, or the cooling fins to dehumidify the air. The water closet acts as a cycling water reservoir in the humidifying mode of operation and as a catch basin in the dehumidifying mode of operation. The drawback of the invention is the limited application to small scale appliances. Further, the device utilizes water absorbent material which after a duration requires replacement.

US9643102B2 teaches a humidification-dehumidification desalination system includes a humidifier, a dehumidifier, and a carrier gas that is humidified in the humidifier and condensed in the dehumidifier to produce purified water. The humidifier preferably includes multiple stages in a staircase configuration in which at least one stage has a perforated or porous plate and the carrier gas is bubbled through the bottom of the plate into the “liquid to be purified” atop the plate. The dehumidifier may also include multiple stages in a staircase configuration in which at least one stage has a perforated or porous plate and the carrier gas is bubbled through the bottom of the plate into the purified liquid atop the plate. The staircase arrangement used in invention is bulky and expensive.

Therefore, there is a need of improving the humidification-dehumidification based fluid treatment systems to overcome abovementioned drawbacks such as improper flow of fluid and gases and large power consumption etc.

OBJECT OF THE INVENTION

The main object of the present invention is to provide a low temperature, high efficiency humidifier-dehumidifier based fluid treatment system comprising of an evaporator unit acting as humidifier and a condenser unit acting as dehumidifier that efficiently separates the dissolved contents from fluid used and produces the pure fluid. The system uses air as a carrier gas which is humidified and dehumidified in a closed loop to purify brine streams.

Another object of the present invention is to provide a humidification and dehumidification based fluid treatment system designed to operate at a temperature between 5-20°C above ambient for humidification and at a temperature 5-20°C below ambient for dehumidification. This low temperature enables low energy consumption in the humidification-dehumidification (HDH) process.

Another object of the present invention is to control the humidification-dehumidification (HDH) process in the humidifier-dehumidifier based fluid treatment system by regulating the relative humidity of the carrier gas by appropriate mixing of the carrier gas with fresh air and exhausting carrier gas to maintain humidity at the specified control limits.

Yet another object of the present invention is to control the humidification- dehumidification (HDH) process in the humidifier-dehumidifier based fluid treatment system by regulating the effluent injection temperature into the evaporator unit.

Yet another object of the present invention is to provide a humidifier-dehumidifier based fluid treatment system that utilizes solar energy, generic heat pumps, low lift heat pumps, vapor absorption machines or other methods of generating heat or cold.

SUMMARY OF THE INVENTION

The present invention provides a humidifier-dehumidifier based fluid treatment system comprising of an evaporator unit acting as humidifier and a condenser unit acting as dehumidifier with intelligently controlled inlet of air/gases and liquid to efficiently separate the dissolved contents from liquid used and produces the pure liquid.

In an embodiment, the present invention provides a humidifier-dehumidifier based fluid treatment system comprising of an evaporator unit acting as humidifier and a condenser unit. The evaporator unit powered by solar energy acts as humidifier consisting of a stack of specially designed pans that when injected with hot effluent and under an intelligent control of air flow maximizes the evaporation rates. The output of this evaporator unit is humidified air and a flow of cold un evaporated effluent. The loss of heat from the fluid as it evaporates reduces its temperature to lower than ambient when the process is properly controlled. This cold fluid -flush is used in condenser unit to cool the humid air to help condense the fluid out. The cold fluid flush reduces the cooling load and improves the efficiency of the system. In addition to the cold flush additional source of cooling is optionally employed to maximize the extraction of vapors from the air. The system utilizes a control unit to intelligently control the induction of fresh air and outlet of humid air to manage the air psychometrics.

The humidifier-dehumidifier based fluid treatment system is a closed system with air circulation and the air is cyclical humidified and dehumidified to extract water. This system utilizes a low lift heat pump and a temperature management unit to maximize the production of pure fluid. The low lift heat pump cools the air to condense water and uses the heat from the air to heat effluent and it is specifically designed to increase and decrease temperatures by 5-10°C.

In another embodiment, the present invention provides a humidifier-dehumidifier based fluid treatment system comprising of a closed housing having a structure including but not limited to an elliptical double walled structure or an elliptical structure, rectangular structure with a separator wall in the centre, at least one fan, injection lines, evaporator unit, condenser unit, at least two flush points, at least two humidity sensors connected with ground, data and live wires and plurality of pans.

Hence, the present invention provides an environment friendly humidifier dehumidifier- based fluid treatment system which is a closed system with maximized production of pure liquid.

BRIEF DESCRIPTION OF DRAWINGS

An understanding of the system of the present invention may be obtained by reference to the following drawings:

Fig. 1(a) is a schematic diagram of the humidifier-dehumidifier based fluid treatment system according to an embodiment of the present invention.

Fig. 1(b) is a schematic diagram of the humidifier-dehumidifier based fluid treatment system according to an alternative embodiment of the present invention. Fig. 2 is a top view of the hiimidifier-dehumidifier based fluid treatment system according to an alternative embodiment of the present invention.

Fig. 3 is a block diagram of working process of the humidifier-dehumidifier based fluid treatment system according to an alternative embodiment of the present invention.

Fig. 4(a) is a graphical representation of a top cross-section of pan, showing air flow and convectional currents with high air-flow rate.

Fig. 4(b) is a graphical representation of top cross-section of pan, showing instabilities and convectional currents with low air-flow rate.

Fig. 5 is a graphical representation of outputs of the simulations of the humidifier- dehumidifier based fluid treatment system.

Figs. 6(a) to 6(d) are graphical representation of high correlation in the humidifier- dehumidifier based fluid treatment system.

DETAILED DESCRIPTION OF THE INVENTION

Many aspects of the invention can be better understood with references made to the drawings below. The components in the drawings are not necessarily drawn to scale. Instead, emphasis is placed upon clearly illustrating the components of the present invention. Moreover, like reference numerals designate corresponding parts through the several views in the drawings. Before explaining at least one embodiment of the invention, it is to be understood that the embodiments of the invention are not limited in their application to the details of construction and to the arrangement of the components set forth in the following description or illustrated in the drawings. The embodiments of the invention are capable of being practiced and carried out in various ways. In addition, the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.

The present invention provides a humidifier-dehumidifier based fluid treatment system that combines use of a solar energy powered evaporator unit and a condenser unit with intelligently controlled inlet of air/gases and liquid which efficiently separates dissolved contents from fluid and maximizes the production of pure fluid. In an embodiment, the present invention provides a humidifier-dehumidifier based fluid treatment system comprising of an evaporator unit acting as humidifier and a condenser unit. Said humidifier-dehumidifier based fluid treatment system comprises of a closed housing, at least one evaporator unit, a condenser unit, a plurality of fans, at least air/gas inlet, a plurality of fluid transmission lines, wherein said evaporator unit utilizes solar energy to heat the fluid for evaporation and said evaporator unit and condenser unit are installed in the closed housing forming a closed loop. The evaporator unit comprises of a plurality of stands with stack of specially designed pans on each stand on which a heated effluent is sprayed through a plurality of injection lines and under an intelligent control of air flow the evaporation rate is maximized. The injection lines are in connection with a liquid reservoir through a water pump and a heating apparatus which uses solar energy for heating the liquid. At the inlet end of the evaporator unit there is a supply of intelligently controlled air/gas through at least one fan. The output of this evaporator is humidified air and a flow of cold unevaporated effluent. The loss of heat from the fluid as it evaporates reduces its temperature to lower than ambient when the process is properly controlled. The cold unevaporated effluent i.e., cold fluid -flush is used in condenser unit to cool the humid air to help condense the fluid out. The condenser unit comprises of a plurality of cooling coils to cool down the humid gas coming out of the evaporator and provide dry gas and recover the pure liquid produced from condensation. The cold fluid flush reduces the cooling load and improves the efficiency of the system by up to 5%. In addition to the cold flush additional source of cooling is optionally employed to maximize the extraction of vapors from the air. The cold unevaporated effluent from evaporator unit is flowed to the condenser unit though a liquid transmission line to cool down the carrier gas flowing the cooling coils. At least one fan installed at the extreme ends of the closed housing help in circulating air in the housing. The system utilizes a control unit to intelligently control the induction of fresh air and outlet of humid air to manage the air psychometrics.

The humidifier-dehumidifier based fluid treatment system is a closed system with air circulation and the air is cyclical humidified and dehumidified to extract water. This system utilizes a low lift heat pump and a temperature management unit to maximize the production of pure fluid. The low lift heat pump is either electrically driven or heat driven by a vapour absorption chiller (VAM). The low lift heat pump cools the air to condense water and uses the heat from the air to heat effluent and it is specifically designed to increase and decrease temperatures by 5-10°C. Further, the humidifier- dehumidifier based fluid treatment system is designed to operate at a temperature between 5-20°C above ambient for humidification and at a temperature 5-20°C below ambient for dehumidification. This low temperature enables low energy consumption in the humidification-dehumidification (HDH) process. The humidification- dehumidification (HDH) process in the humidifier-dehumidifier based fluid treatment system is controlled by regulating the relative humidity of the carrier gas by appropriate mixing of the carrier gas with fresh air and exhausting carrier gas to maintain humidity at the specified control limits. Also, the humidification-dehumidification (HDH) process is controlled by regulating the effluent injection temperature into the evaporator unit.

In an alternative embodiment, the present invention provides a humidifier-dehumidifier based fluid treatment system with an evaporator unit and a condenser unit housed in a closed housing wherein the condenser unit optionally uses a cooling apparatus with an industrial refrigerant to maximize the performance and a fog catcher at the outlet of the condenser unit to maximize the condensation without use of any additional energy.

Referring to Fig. 1(a), a schematic diagram of the humidifier-dehumidifier based fluid treatment system is shown which is in accordance to an embodiment of the present invention. The humidifier-dehumidifier based fluid treatment system 10 comprises of a closed housing 11, at least one evaporator unit 12 acting as humidifier, a condenser unit 13 acting as dehumidifier, a plurality of fan 14, at least air/gas inlet 15, a plurality of liquid transmission lines 16, wherein said evaporator unit 12 utilizes solar energy to heat the liquid for evaporation and said evaporator unit 12 and condenser unit 13 are installed in the said closed housing 11 to form a closed loop to provide a humid gas out of evaporation and produce pure liquid out of condensation. The evaporator unit 12 includes a fluid reservoir 17 and a heating apparatus 18. The evaporator unit 12 has a plurality of injection lines 22 which draw heated fluid/effluent from the fluid reservoir 17 through heating apparatus 18 using a water pump 29. The output from the evaporator unit 12 is humidified air and a flow of cold unevaporated effluent. The cold unevaporated effluent i.e., cold fluid -flush from evaporator unit 12 is flown through liquid transmission line 16 for use in condenser unit 13 to cool the humid air to help condense the fluid out. A fan 14 is installed at the extreme ends of the housing 11 help in circulating air in the closed housing 11. The heating apparatus 18 comprises of a low lift heat pump 27 and a temperature management unit 28 that moves and cools the air to condense water and uses the heat from the air to heat the fluid/effluent. The low lift heat pump 27 is specifically designed to increase and decrease temperatures by 5-10°C. The closed housing is having a structure including but not limited to an elliptical double walled structure or an elliptical structure, rectangular structure with a separator wall in the centre.

Referring to Fig. 1(b), a schematic diagram of the humidifier-dehumidifier based fluid treatment system is shown which is in accordance with an alterative embodiment of the present invention. The humidifier-dehumidifier based fluid treatment system 10 comprises of a closed housing 11, at least one evaporator unit 12 having a fluid reservoir 17 and a heating apparatus 18, a condenser unit 13, a plurality of fan 14, at least air/gas inlet 15, a plurality of liquid transmission lines 16. The heating apparatus 18 utilizes solar energy to heat the liquid for evaporation. The condenser unit 13 uses a cooling apparatus 19 with an industrial refrigerant to maximize the performance and a fog catcher 20 at the outlet end of the condenser unit 13 to maximize the condensation with use of any additional energy.

Referring to Fig. 2, a block diagram of working process of the humidifier-dehumidifier based fluid treatment system is illustrated. Two fluid circuits are maintained to enable efficient heating of the effluent and further used in cooling. One circuit maintains the controlled injection of the hot effluent into the evaporator unit 12 via an injection controller 30. The fluid flows across the pans, evaporating and cooling in the process. The effluent cool downs to ambient or lower even when pre-heated to 60°C or higher.

Considering the equation for dew point:

Wherein, with high RH values i.e. more than 60% after the humidifier, the cold flush is used to cool the moist air down to (or at least close to) the dew point required. The flush is then recollected and heated to be injected again.

The refrigerant is cycled through the cold side of the heat pump 27 and is pumped through a condenser module. This happens after the cold flush has already cooled the saturated air. The refrigerant then works to remove the latent heat from the vapour and efficiently condense the water out. Additionally, the flow of refrigerant is controlled by a control unit 26. The fan 14 speed in the evaporator unit 12 is lowered to maximize the time die air spends cooling.

Referring to Fig. 3 and according to another embodiment, a top view of the humidifier- dehumidifier based fluid treatment system is illustrated, comprising of a closed housing 11 having a structure including but not limited to an elliptical double walled structure or an elliptical structure, rectangular structure with a separator wall 21 in the centre, at least one fan 14, injection lines 22, evaporator unit 12, condenser unit 13, at least two flush points 23, at least two humidity sensors 24 connected with ground, data and live wires and plurality of pans 25.

EXAMPLE

EXPERIMENTATION ANALYSIS

The humidifier-dehumidifier based fluid treatment system 10 was further test to showcase the increased efficiency. The air flow inside the system 10 is analysed by computational fluid dynamics simulation methodology and the results of the simulation are presented in Fig. 4(a) and Fig. 4(b). Fig. 4(a) shows a top cross-section of pan, showing air flow and convectional currents with high air-flow rate i.e., more than 5 m/s, whereas Fig. 4(b) shows top cross-section of pan, showing instabilities and convectional currents with low air-flow rate i.e., less than 5 m/s. Moreover, currents due to turbulence aid in the process of evaporation.

Another experimentation was conducted to showcase the purity of water obtained from the humidifier-dehumidifier based fluid treatment system 10 and the input conditions for this experimentation are represented in Table 1.

Table 1

Input conditions for experimentation

A simulation was programmed to predict the behaviour of the system 10 for some sets of effluent and condenser temperatures that are presented in Table 2 and output of the simulation is presented in Table 3.

Table 2

Sets of effluent and condenser temperatures using which simulation was programmed to predict the behaviour of system

Table 3

Output of simulation for variables

Averaged results of three trials from experimental setup is given in Table 4.

Table 4

Averaged Results

Fig. 5 represents a graphical representation of outputs of the simulations from which a noticeably good correlation factor between the simulated data and experimental data was observed. An average r-squared value of 0.98 is observed which indicates a high correlation as depicted in Figs. 6(a) to 6(d).

A range for the amount of water generated (non-ideal ambient humidity and temperature to ideal ambient humidity and temperature) are in litre/hour/meter square where it refers to the area of pan utilized. In ideal case: ambient RH is 50%, ambient temperature is 35°C, in which after evaporation the liquid temperature is 28.4376°C and the water evaporated is 1.0596 LPH, whereas after condensing process, the amount of water condensed is 0.64685 LPH. In non-ideal case, ambient RH is 80%, ambient temperature is 25°C, wherein after evaporation liquid temperature is 25.0273°C and water evaporated is 0.96836 LPH, after condensing process the amount of water condensed is 0.29432 LPH.

Two existing methods for testing high-efficiency evaporation include WAIV (Wind Assisted Intensive evaporation) systems and solar stills. The advertised capacity for evaporation for WAIV1 systems ranges between 2000-5000 gallons a day per unit. Each unit has a wetted surface area of 1.4 acres or 5600 square m. Therefore, the evaporation rate is (at the higher end) 3.8 L/day/m² which amounts to 0.16 L/h/m². In similar conditions (no liquid pre-heating) the system 10 achieves an evaporation rate of 0.31 L/h/m² (ambient temperature: 35°C; ambient humidity: 60%; no liquid preheating; fan speed at 2 m/s). Solar stills tested in temperate regions report an average evaporation rate of 2.9 L/day /meter square. Again, the solar stills are a passive system but are useful in collecting distillate.

Therefore, the present invention provides a humidifier-dehumidifier fluid treatment system with maximized evaporation and condensation to efficiently separate the dissolved contents from fluid used and maximize production of pure liquid using intelligently controlled inlet of gas/air and liquid in the system.

The foregoing description of embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principals of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.

Claims

CLAIMS We claim:

1. A humidifier-dehumidifier based fluid treatment system (10) comprising of: a closed housing (11); at least one evaporator unit (12) acting as humidifier; a condenser unit (13) acting as dehumidifier, a plurality of fan (14); at least air/gas inlet (15); a control unit; and a plurality of liquid transmission lines (16); wherein, said evaporator unit (12) includes a fluid reservoir (17) and a heating apparatus (18), a plurality of injection lines (22) for drawing out heated fluid/effluent from said fluid reservoir (17) through heating apparatus (18) using a pump (29), plurality of stands with stack of pans (25) on each stand on which said heated effluent is sprayed via said injection lines (22); said evaporator unit (12) utilizes renewable energy to heat said fluid/effluent for evaporation and the controlled carrier gas/air flow maximizes the evaporation rate; said evaporator unit (12) and condenser unit (13) are installed in said closed housing (11) to form a closed loop for providing a humid gas out of evaporation and produce pure liquid out of condensation, due to which said humidifier-dehumidifier based fluid treatment system (10) operates at an ambient temperature, thereby reducing energy consumption; said heating apparatus (18) comprises of a low lift heat pump (27) and a temperature management unit (28) that moves and cools the air to condense water and uses the heat from the air to heat the fluid/effluent; said low lift heat pump (27) cools the air to condense water and uses the heat from the air to heat effluent and is designed to increase and decrease temperatures; said condenser unit (13) optionally uses a cooling apparatus (19) with an industrial refrigerant to maximize the performance and a fog catcher (20) to maximize the condensation without use of any additional energy; said evaporator unit (12) releases humidified air and a flow of cold unevaporated effluent and a cold unevaporated effluent from said evaporator unit (12) is flown through said liquid transmission line (16) for use in said condenser unit (13) for cooling the humid air to help condense said fluid flush out via plurality of flush points (23); said fan (14) is installed said closed housing (11) to help in circulating of air inside said closed housing (11); and said humidifier-dehumidifier based fluid treatment system (10) includes at least two humidity sensors (24) and a control unit to control the induction of flesh air and outlet of humid air to manage the air psychometrics.

2. The humidifier-dehumidifier based fluid treatment system (10) as claimed in claim 1, wherein said closed housing (11) is having a structure including but not limited to an elliptical double walled structure or an elliptical structure/rectangular structure with a separator wall (21) in the center.

3. The humidifier-dehumidifier based fluid treatment system (10) as claimed in claim 1, wherein said pump (29) is preferably a water pump.

4. The humidifier-dehumidifier based fluid treatment system (10) as claimed in claim 1, wherein said renewable energy includes but not limited to solar energy, wind energy.

5. The humidifier-dehumidifier based fluid treatment system (10) as claimed in claim 1, wherein said system (10) uses air as a carrier gas which is humidified and dehumidified in a closed loop between evaporation unit (12) and condenser unit

(13).

6. The humidifier-dehumidifier based fluid treatment system (10) as claimed in claim 1, wherein said humidifier-dehumidifier based fluid treatment system (10) is operated in said ambient temperature that ranges between 5°C to 20°C and is controlled by regulating relative humidity of the carrier gas by appropriate mixing of the carrier gas with fresh air and exhausting carrier gas to maintain humidity at the specified control limits.

7. The humidifier-dehumidifier based fluid treatment system (10) as claimed in claim 1, wherein said injection lines (22) are controlled by an injection controller (30).

8. The humidifier-dehumidifier based fluid treatment system (10) as claimed in claim 1, wherein said condenser unit (13) comprises of a plurality of cooling coils to cool down the humid gas coming out of the evaporator unit (12) and provide dry gas and recover the pure liquid produced from condensation.

9. The humidifier-dehumidifier based fluid treatment system (10) as claimed in claim 1, wherein said fog catcher is assembled at the outlet of said condenser unit (13) to maximize the condensation.

10. The humidifier-dehumidifier based fluid treatment system (10) as claimed in claim 1, wherein said low lift heat pump (27) increases and decreases temperatures ranging from 5 to 10°C and either electrically driven or heat driven by a vapor absorption chiller (YAM).

11. The humidifier-dehumidifier based fluid treatment system (10) as claimed in claim 1, wherein said fan (14) is preferably installed at the extreme ends of said closed housing (11).

12. The humidifier-dehumidifier based fluid treatment system (10) as claimed in claim 1, wherein said evaporator unit (12) produces said cold fluid flush that reduces the cooling load and improves the efficiency of the system (10) in range from 5% to 6%.

13. The humidifier-dehumidifier based fluid treatment system (10) as claimed in claim 1, wherein said refrigerant’s flow is controlled by a control unit (26).

14. The humidifier-dehumidifier based fluid treatment system (10) as claimed in claim 1, wherein said evaporator unit (12) includes a provision of an additional source of cooling optionally employed to maximize the extraction of vapours from the air.