Portable air conditioner

Abstract

A portable air conditioner comprises a tank for storing a liquid therein, a plurality of tubes, and at least one fin disposed between adjacent tubes. The tubes are spaced from one another defining an air passageway therebetween having an air inlet and a dry air outlet. Each tube has a first end extending into the tank in fluid communication with the liquid and a second end extending opposite the tank defining a wet air outlet and a wicking material disposed therein and in fluid communication with the liquid. A sheet valve sealingly engages the dry air outlet and the wet air outlet and is moveable for adjusting an amount of air flow exiting from the dry air outlet and the wet air outlet. At least one aperture is defined within each of the tubes between the ends to divert air flowing through the air passageway into the tubes.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention relates to a portable air conditioner, and more specifically to a personal, portable air conditioner that does not require a compressor and that is able to provide dry air as well as wet air separately.

2. Description of the Related Art

Various types of air conditioners are well known. The most common type of air conditioner is commonly referred to as a vapor compression air conditioner. The vapor compression air conditioner comprises a condenser, an evaporator, a compressor, and an expansion device operating in a closed loop. A working fluid circulates within the closed loop. The working fluid enters the compressor as vapor under low pressure and the compressor compresses the vapor to form a super heated vapor that passes through the condenser. A blowing device moves outside air across the condenser and the condenser gives off heat to the outside air thereby warming it. The working fluid exits the condenser as a high pressure liquid and passes through the expansion device to lower the pressure. The low pressure liquid then enters the evaporator and a second blowing device moves outside air across the evaporator resulting in the working fluid evaporating. The evaporation of the working fluid draws heat from outside air that is cooled. One drawback of the vapor compression air conditioners is the requirement of the two heat exchangers, two blowing devices, the working fluid, and the compressor. The vapor compression air conditioners tend to be large and bulky and are generally not portable because of the numerous components. The use of a compressor significantly impacts the weight and bulkiness of the air conditioner resulting in a less portable air conditioner. Moreover, the working fluids are generally not environmentally safe and may be possibly harmful or toxic if exposed to the user.

Another common type of air conditioner is referred to as a direct evaporative air conditioner. The direct evaporative air conditioner comprises a liquid source, such as a pool of water, and hot air passes directly over the surface of the liquid. Energy from the air is transferred for evaporating the liquid, which results in a drop of the temperature of the air. As the temperature drops, the absolute humidity of the air increases. However, one draw back to direct evaporative air conditioners, commonly called “swamp coolers”, is that the conditioned air carries odors that are present in the liquid source. One example of a direct evaporative air conditioner utilizes a frozen liquid as a source to cool the air. These types of air conditioners are able to provide cooling and possibly filtration of the air. However, these air conditioners do not provide the capability dividing an ambient air stream into a desired dry air stream and a humidified air stream. Further, these air conditioners do not include adjustment mechanism to regulate the amount of cooling that is occurring with the air to coincide with the comfort of the user.

Still another common type of air conditioner is an indirect evaporative air conditioner. Indirect evaporative air conditioners generally have a wet channel with a first air moving device and a dry channel with a second air moving device. The first air moving device directs a stream of air through the wet channel and the second air moving device directs air through the dry channel. The air flowing through the wet channel carries water vapor that is evaporated from the air contacting the dry channel. These types of indirect evaporative air conditioners are inefficient because of the two air moving devices. Moreover, the two devices result in a more heavy and bulky, i.e., less portable, air conditioner.

Accordingly, it would be advantageous to provide a portable air conditioner that overcomes the inadequacies that characterize the related art air conditioners.

SUMMARY OF THE INVENTION AND ADVANTAGES

The subject invention provides a portable air conditioner comprising a tank for storing a liquid therein, a plurality of tubes, and at least one fin disposed between adjacent tubes. The tubes are spaced from one another defining an air passageway therebetween having an air inlet and a dry air outlet for dispensing dry air therefrom. Each of the tubes have a first end extending into the tank in fluid communication with the liquid and a second end extending opposite the tank defining a wet air outlet for dispensing wet air therefrom and a wicking material disposed therein. The air conditioner also includes a sheet valve sealingly engaging the dry air outlet and the wet air outlet. The sheet valve is moveable for adjusting an amount of air flow exiting from the dry air outlet and the wet air outlet. The subject invention also includes at least one aperture defined within each of the tubes between the ends for diverting air flowing through the air passageway into the tubes and exiting through the wet air outlet.

The subject invention overcomes the inadequacies that characterize the related art air conditioners. Specifically, the subject invention provides an air conditioner that cools air without requiring a compressor, which results in a light weight portable unit. The subject invention can also separately cool the air and provide humidification to the air separately. The air conditioner according to the subject invention may also adjust the amount of cooling and/or humidification to more closely coincide with the comfort of the user.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a front perspective view of a portable air conditioner according to the subject invention;

FIG. 2 is a rear perspective view of the portable air conditioner shown in FIG. 1;

FIG. 3 is a front perspective view of the portable air conditioner of FIG. 1 having a fan module removed therefrom;

FIG. 4 is an exploded front perspective view of the portable air conditioner shown in FIG. 1;

FIG. 5 is a schematic circuit diagram of the portable air conditioner;

FIG. 6 is a representation of wet and dry air streams flowing through the portable air conditioner on a psychrometric chart.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, a portable air conditioner is shown generally at 10 in FIG. 1. It is to be appreciated that the portable air conditioner 10 may be used by a single user, i.e., personal. Further, the portable air conditioner 10 does not require a compressor thereby reducing the weight of the air conditioner 10 and increasing the portability. The portable air conditioner 10 is particularly useful in buildings as well as in outdoor environments. For example, the air conditioner 10 may be used during war times or in the medical field. The subject invention is capable of providing sufficiently conditioned air in various climates, such as hot and dry climates, hot and humid climates, or cool and dry climates. The portable air conditioner 10 of the subject invention may also be used in series with a heater, such as an electric heater to further warm air exiting therefrom.

The portable air conditioner 10 generally comprises a tank 12 for storing a liquid therein, a plurality of tubes 14, and at least one fin 16 disposed between adjacent tubes 14. The tank 12 may be formed of various materials, such as plastic or metal materials. However, in order to reduce the weight of the air conditioner 10, it is preferable to form the tank 12 from plastic materials. Moreover, the tank 12 may be formed from a transparent material in order to view the level of the liquid within the tank 12. The tank 12 may also be omitted or remain unfilled to operate the air conditioner 10 as a ventilator.

The tank 12 is shown in the Figures as a generally rectangularly shaped tank 12 with four sides having slots 18 (shown best in FIG. 4) in a top for receiving the tubes 14. The connection between the tubes 14 and the tank 12 may be sealed by any well known sealing methods, if desired, to prevent the liquid from escaping. The tank 12 also includes a liquid inlet 20 for allowing additional liquid to be supplied to the tank 12. The liquid inlet 20 may be able to be connected to a water source, such as a faucet or a hose. The tank 12 optionally may include a sensor (not shown) to indicate the level of the liquid therein or have a valve (not shown) connected to the water supply for actuating a filling mechanism to re-fill the tank 12. The liquid within the tank 12 is preferably water; however, other liquids may be utilized without deviating from the subject invention.

Referring back to FIG. 1, the air conditioner 10 has the plurality of tubes 14 spaced from one another. It is to be appreciated by those of ordinary skill in the art that the air conditioner 10 may be manufactured with as few as two tubes 14 or with as many as fifty tubes 14. The number of tubes 14 is not intended to limit the subject invention. The tubes 14 are spaced from one another and define an air passageway 22 therebetween. The air passageway 22 has an air inlet 24 for ambient air 100 to enter and a dry air outlet 26 for dispensing dry air 110 therefrom. In other words, the air passageway 22 acts as a dry channel. Ambient air enters the air inlet 24 as illustrated by arrow 100 and dry air exits the dry air outlet 26 as illustrated by arrow 110, both in FIG. 1.

The subject invention may also include a fan module 28 adjacent the air inlet 24 for directing a flow of ambient air 100 though the air passageway 22 as shown in FIG. 1. The fan module 28 increases the amount of ambient flowing into the air passageway 22. The fan module 28 may be removable from the air conditioner 10 or permanently mounted thereon. The fan module 28 may be any well known type of fan, such as an axial fan or centrifugal fan. However, it is preferred that an axial fan is used to concentrate the flow of ambient air 100 through the air passageway 22.

The portability of the air conditioner 10 is increased by providing a power supply to operate the fan module 28. It is desirable that the power supply be small and light weight and be able to sufficiently power the fan module 28. For example, the power supply may be a battery 30. Alternatively, the power supply may comprise a solar panel 32 with a plurality of solar cells 34 as shown in the Figures. This is particularly advantageous if the portable air conditioner 10 is used in outdoor environments. The use of the solar panels 32 result in a self-adjusting system for comfort cooling. In other words, if the sun is present, more cooling will be needed and the solar panels 32 will provide more voltage for operating the fan module 28.

The subject invention may also utilize a combination of power supplies. A schematic circuit diagram of the air conditioner 10 is shown in FIG. 5. The circuit diagram includes a dual power supply, the solar panel 32, and an auxiliary supply, such as the battery 30. The solar panel 32 supplies power to the fan module 28 through a first diode 40 and the air conditioner 10 has two ground points 38 that complete the circuit. The battery 30 feeds power to the fan module 28 through a second diode 36. Thus, the fan module 28 may be powered by whichever power supply has the higher voltage. The first diode 40 prevents back feeding power from the battery 30 into the solar panel 32 and the second diode 36 prevents back feeding power from the solar panel 32 into the battery 30. As another power supply, a hand generator (not shown) may also be used in place of either the solar panel 32 or the battery 30.

Referring back to FIGS. 1 through 4, each of the tubes 14 have a first end 42 extending into the tank 12 in fluid communication with the liquid and a second end 44 extending opposite the tank 12. The first end 42 is sufficiently open to allow the liquid to enter inside of the tube 14. The second end 44 extends opposite the tank 12 defining a wet air outlet 46 for dispensing wet air 120 therefrom, which is illustrated by arrow 120 in FIG. 1. In other words, the inside of the tubes 14 defines a wet channel. The tubes 14 may be formed of various materials that are light weight, such as plastic or metal materials. Further, the tubes 14 are preferably generally flat, oval shaped tubes 14, however, various shapes of tubes 14 may be used with the subject invention without being limited to the embodiments shown.

At least one fin 16 is disposed between adjacent tubes 14. Preferably, an array of fins 16 are disposed between adjacent pairs of tubes 14 as understood by those of ordinary skill in the art. The fins 16 are preferably formed of a material having good heat transfer properties. One suitable material would include a metal material. The fin 16 may be a plain fin, a corrugated fin, or a louvered fin. Preferably, the fin 16 is a louvered fin for allowing air to pass vertically through the air passageway 22 and increase heat transfer therebetween.

The tubes 14 also include at least one aperture 48 defined within each of the tubes 14. The apertures 48 are located between the ends 42, 44 for diverting air flowing through the air passageway 22 into the tubes 14 and exiting through the wet air outlet 46. As shown in the Figures, the apertures 48 are located between the first and second ends 42, 44 and are closer to the first end 42, while remaining above the tank 12. In other words, as ambient air 100 flows through the air passageway 22, a fraction of the air is diverted through the aperture 48 and into the tube 14. The number and size of apertures 48 are determined to ensure a desired amount of air is flowing through the dry air outlet 26 and the wet air outlet 46.

A wicking material 50 is disposed within at least one of the tubes 14 and is in fluid communication with the liquid. Preferably, the wicking material 50 is a fibrous material, such as fabric or cloth. The wicking material 50 wicks the liquid from the tank 12 via capillary action up the tube 14. Preferably, the wicking material 50 extends along a substantial portion of the tube 14, such as more than fifty percent of the length of the tube 14. However, different amounts of wicking material 50 may be used to achieve various results. The ambient air 100 entering the air passageway 22 transmits energy to the fin 16 and through the tube 14 to evaporate the liquid in the wicking material 50. As the liquid evaporates, the humidity of air exiting the wet air outlet 46 increases in humidity. Further, the air passing through the air passageway 22 and exiting the dry air outlet 26 is cooled. As will be described further below, the dry air 110 exiting the dry air outlet 26 may have the same humidity as the ambient air 100 entering the air passageway 22.

A sheet valve 52 sealingly engages the dry air outlet 26 and the wet air outlet 46. The sheet valve 52 is moveable relative to the air outlets 26, 46 for adjusting an amount of air flow exiting from the dry air outlet 26 and the wet air outlet 46. The air conditioner 10 according to the subject invention is operable in four modes: 1) cooling mode, 2) ventilation mode, 3) heating mode, and 4) humidification mode. In the cooling mode, the sheet valve 52 is in a halfway position, as shown in the Figures, such that half of the dry air outlet 26 is blocked by the sheet valve 52. Since the ambient air 100 is not able to pass straight through the air passageway 22, the ambient air 100 remains in contact with the fins 16, thereby transferring additional energy to evaporate the liquid on the wicking material 50. Also, the ambient air 100 is forced downward and into the apertures 48 thereby increasing the amount of wet air 120 exiting the wet air outlet 46.

In the ventilation mode, the sheet valve 52 would be positioned entirely closing the wet air outlet 46, thereby passing all the ambient air 100 straight through the air passageway 22. The dry air 110 will likely have the same humidity as the ambient air 100 with a lower temperature when exiting the dry air outlet 26. In the heating mode, an additional heater (not shown) may be positioned adjacent the dry air outlet 26 to heat the dry air 110. In the humidification mode, the sheet valve 52 is positioned entirely closing the dry air outlet 26, forcing all the ambient air 100 through the apertures 48 and into the tubes 14 resulting in an increased flow of wet air 120 exiting the wet air outlet 46.

The subject invention also includes an adjustment mechanism 54 operatively connected to the sheet valve 52 for moving the sheet valve 52. The adjustment mechanism 54 can be operated manually or automatically. Adjusting the sheet valve 52 serves as a thermostat to regulate a desired temperature by adjusting amounts of air flowing therefrom. In the embodiment shown, the adjustment mechanism 54 is a knob that allows a user to rotate the knob and move the sheet valve 52 accordingly depending upon the preference of the user. It is to be appreciated by those of ordinary skill in the art that other adjustment mechanisms 54 may be used with the subject invention.

In order to ensure the flow of the ambient air 100 through the air conditioner 10, at least one first flow plate 56 is disposed between the tubes 14 and adjacent the second ends 44 for sealing the air passageway 22. In other words, the first flow plate 56 seals the top of the air passageway 22 to reduce ambient air 100 from escaping from the top of the air condition. Referring to FIG. 4, two first flow plates 56 are shown sealing between the three tubes 14. Additionally, at least one second flow plate 58 is disposed adjacent the dry air outlet 26 for sealing the tubes 14. Said another way, the second flow plates 58 prevent ambient air 100 from escaping from the air passageway 22. In FIG. 4, three second flow plates 58 are illustrated positioned at the rear of each of the tubes 14. Standard sealing devices or seals may be used in place of either or both of the first and second flow plates 56, 58 so long as the ambient air 100 sufficiently contacts the fins 16 to transfer energy therebetween.

Another feature of the subject invention is that a cartridge 60 may be disposed adjacent at least one of the dry air outlet 26 and the wet air outlet 46. The cartridge 60 may be a filter to remove particles from either wet air 120 or the dry air 110 or may be an aroma filter to add an aroma to the same. In one embodiment, the cartridge 60 is disposed in a cartridge slot 62 that may be defined between the sheet valve 52 and the humid or dry air outlets 26. In FIG. 2, the cartridges 60 are shown disposed within the dry air outlet 26. An additional filter (not shown) may be mounted between the air inlet 24 and the fan module 28, if desired, to remove particles from the ambient air 100, such as sand, dirt, or the like, prior to entering the air conditioner 10.

Referring to FIG. 6, the state of the ambient air 100 is shown as it enters the portable air conditioner 10 and flows through the passageways 22 exiting as the dry air stream 110. It also shows the state of the wet air stream 120 fractioned off from the incoming air stream at the apertures 48 and directed through the wet air passageways 46.

The horizontal axis of the psychrometric chart represents the dry bulb temperature, T_db, of air while the vertical axis represents the absolute humidity, ω, of air, which is the mass of water vapor in unit mass of dry air 110. The other measure of the moisture content of air, namely relative humidity, φ, is also indicated on the psychrometric chart as a parameter on the two curves labeled φ=1 and φ=φ_i. The curve φ=1 represents the fully saturated air with 100% relative humidity and the curve φ=φ_i represents the partially saturated incoming ambient air 100 with relative humidity φ_i<1. Relative humidity, φ, is the ratio of the mass of water vapor in a given volume of air to that necessary to saturate it at the same temperature.

The state of ambient air stream 100 entering the portable air conditioner 10 with dry bulb temperature, T_i, relative humidity, φ_i, and absolute humidity φ_i is represented by point on the psychrometric chart. The fraction of the ambient air stream 100 that moves along the line 1→3 with its absolute humidity, ω_i, remaining fixed but relative humidity increasing from φ_i to 1 is the dry air 110. At the same time the dry bulb temperature, T_i, of the dry air stream 110 decreases from T_i to T_dpi, which is the dew point temperature of air corresponding to the inlet conditions. It is the lowest dry bulb temperature that the dry air stream 110 can attain with fixed absolute humidity, ω_i. T_dpi is expressible as $\begin{array}{cc}{T}_{\mathrm{dpi}}=T_{\mathrm{wt}}{\left\{1-\frac{1}{\alpha }\ln \left[\frac{{\omega }_i{P}_{\mathrm{amb}}/P_{\mathrm{wt}}}{{\omega }_i+M_w/M_a}\right]\right\}}^{-3/4}& \left(1\right)\end{array}$

where

T_wt is the triple point temperature of water=491.6880° R.

P_wt is the triple point pressure of water=0.088663 psi.

P_amb is the atmospheric pressure=14.696 psi.

M_a is the molecular weight of air=28.9645 lb_m/lbmole.

M_w is the molecular weight of water=18.0152 lb_m/lbmole.

ω_i is the absolute humidity of the incoming air, lb_m H₂O/lb_m dry air.

α is a dimensionless constant=15.0197.

In FIG. 6, the temperature increases from left to right and the absolute humidity increases from bottom to top. It may be noted that dew point temperature is the lowest temperature that air can attain without any moisture addition. As the air temperature tends to the dew point, its capacity to hold water vapor diminishes and upon reaching the dew point it no longer can hold the water vapor, which then condenses out of the air as liquid water.

In view of the inherent inefficiencies in the system, the actual dry bulb temperature, T_do, attained by the dry air stream 110 is somewhat higher than T_dpi as indicated at point on the psychrometric chart.

In the maximum comfort cooling mode, the wet air stream 120 exiting through the wet passageways 46 takes the path 1→6 indicated on the psychrometric chart. In this mode of operation, the dry bulb temperature of the wet air stream 120 remains fixed at T_i, but its absolute humidity increases from ω_i to ω_∞ with relative humidity increasing from φ_i to 1. The absolute humidity, ω_∞, of the wet air stream 120 exiting the wet passageways 46 is expressible as $\begin{array}{cc}{\omega }_{\infty }=\frac{M_w/M_a}{\left(P_{\mathrm{amb}}/P_{\mathrm{wt}}\right)\exp \left\{\alpha \left[{\left(T_{\mathrm{wt}}/T_i\right)}^{4/3}-1\right]\right\}-1}& \left(2\right)\end{array}$

Corresponding to the ω_∞, the dry bulb temperature T_do attained by the dry air stream 110 flowing through the dry passageways 22 is expressible as $\begin{array}{cc}{T}_{\mathrm{do}}=T_i\frac{\lambda h_{\mathrm{fg}}\left({\omega }_{\infty }-{\omega }_i\right)}{c_{\mathrm{pa}}}& \left(3\right)\end{array}$

where in addition to the previously defined symbols

λ is the mass fraction of the ambient air stream 100 diverted into the wet passageways 46, i.e., it is the ratio of the mass flow rate of the wet air stream 120 to the mass flow rate of the ambient air stream 100.

c_pa is the isobaric specific heat of air, Btu/lb_m° R.

h_fg is the latent heat of evaporation of water given as $\begin{array}{cc}{h}_{\mathrm{fg}}={\beta \left(1-\frac{T_i}{T_c}\right)}^{3/8}& \left(4\right)\end{array}$

where in addition to the previously defined symbols

β is a constant=1300.26 Btu/lb_m.

T_i is the dry bulb temperature of the incoming ambient air, ° R.

T_c is the critical temperature of water=1165.11° R.

The absolute humidity ω_i of the incoming ambient air 100 is expressible as $\begin{array}{cc}{\omega }_i=\frac{\left(M_w/M_a\right){\varphi }_i}{\left(P_{\mathrm{amb}}/P_{\mathrm{wt}}\right)\exp \left\{\alpha \left[{\left(T_{\mathrm{wt}}/T_i\right)}^{4/3}-1\right]\right\}-{\varphi }_i}& \left(5\right)\end{array}$

where in addition to the previously defined symbols φ_i is the relative humidity of the incoming ambient air 100.

The rate of evaporation of water in the maximum comfort cooling mode is expressible as
{dot over (m)}_w=λ{dot over (m)}_a(ω_∞−ω_i)  (6)

where in addition to the previously defined symbols

{dot over (m)}_w is the rate of evaporation of water in the portable air conditioner 10, lb_m/min.

{dot over (m)}_a is the mass flow rate of ambient air 100 flowing into the portable air conditioner 10, lb_m/min.

The mass fraction, λ, of air required to attain the lowest comfort cooling temperature, T_dpi, is expressible as
λ=c_pa(T_i−T_dpi)/(ω_∞−ω_i)h_fg  (7)

where all the symbols have been previously defined.

In the humidification mode, the incoming ambient air stream 100 is directed through the wet passageways 46 by closing the dry passageways by means of the sheet valve 52. In this case, the path taken by the wet air stream 120 is indicated by the line 1→5 on the psychrometric chart. In the humidification mode, the lowest dry bulb temperature attained by the wet air stream 120 is the wet bulb temperature T_dpo corresponding to the absolute humidity ω_w indicated on the psychrometric chart. The wet bulb temperature is the temperature attained by air as it becomes saturated with water vapor evaporating into the air from an external source, such as saturated wicking material 50 lining the passageways 46, resulting in an increase in the absolute humidity of the air. The wet bulb temperature must be distinguished from the dew point temperature, which is the temperature attained by air as it becomes saturated with water vapor within the air itself, i.e., without water addition from an external source. Thus unlike the wet bulb temperature the dew point temperature is attained with no change in the absolute humidity of the air.

T_dpo and ω_w can be determined using the following two independent relations expressing ω_w explicitly as a function of T_dpo:
ω_w=M_w/M_a/(P_amb/P_wt)exp{α[(T_wt/T_dpo)^4/3−1]}−1  (8)
ω_w=ω_i+(c_pa+ω_ic_pw)(T_i−T_dpo)/h_ao+32c_f−(c_f−c_pw)T_dpo  (9)

where in addition to the previously defined symbols

c_pa is the isobaric specific heat of air=0.24 Btu/lb_m° R.

c_pw is the isobaric specific heat of water vapor=0.444 Btu/lb_m° R.

c_f is the isobaric specific heat of liquid water=1 Btu/lb_m° R.

h_ao is the reference enthalpy of air=1061 Btu/lb_m.

Unfortunately Eqs. (8) and (9) cannot be solved in closed form to determine T_dpo and ω_w explicitly. They need to be solved iteratively to determine T_dpo and ω_w. The iterative procedure can proceed as follows. Assume an initial lower bound value of T_dpo=T_dpi where T_dpi is given in Eq. (1). With this value of T_dpo determine ω_w using Eqs. (8) and (9). If the two values of ω_w do not match, assume a higher value of T_dpo and calculate a new set of ω_w values using Eqs. (8) and (9). Continue the iterative procedure till the two values of ω_w match. The corresponding assumed value of T_dpo will then represent the desired value of T_dpo.

In the humidification mode, the entire ambient air stream 100 is directed through the passageways 46. The humidified air emerges from air conditioner 10 as cold and wet air stream 120 with no air emerging from the dry passageways 22. In other words, the mass flow rate of the wet air stream 120 is equal to the mass flow rate of the ambient air stream 100. In this case, the rate of consumption of liquid water to produce the absolute humidity and the wet bulb temperature given by Eqs. (8) and (9) is given by
{dot over (m)}_w={dot over (m)}_a(ω_w−ω_i)  (10)

Having presented the useful analytical relations, numerical examples are presented next to illustrate some useful quantitative results generated therefrom for the portable air conditioner 10.

EXAMPLE

Calculate the lowest temperature of the conditioned dry air stream 110 produced by the portable air conditioner 10 if the dry bulb temperature of the ambient air 100 is 100° F. and its relative humidity is 40%.

The lowest temperature attained by the dry air stream 110 in the portable air conditioner 10 is the dew point temperature T_dpi given by Eq. (1) corresponding to the initial absolute humidity ω_i, which needs to be determined first corresponding to the given ambient air 100 temperature T_i=100° F.=559.67° R and the relative humidity φ_i=0.40. Introducing these values into Eq. (5) together with M_a=28.9645 lb_m/lbmole, M_w=18.0152 lb_m/lbmole, P_amb=14.696 psi, P_wt=0.088663 psi and T_wt=491.6880° R, we obtain ω_i=0.016685 lb_m H₂O/lb_m dry air 110. Introducing this value of ω_i together with α=15.0197 into Eq. (1), we obtain the value of the lowest temperature attained by the air as T_dpi=531.1° R=71.4° F.

Example 2

Determine the maximum absolute humidity of the wet air stream 120 attained in the portable air conditioner 10 in the comfort cooling mode when the ambient air 100 temperature is 100° F.=559.67° R.

The maximum absolute humidity ω_∞ of the wet air stream 120 attained in the portable air conditioner 10 is given by Eq. (2). Introducing M_a=28.9645 lb_m/lbmole, M_w=18.01521 lb_m/lbmole, P_amb=14.696 psi, P_wt=0.088663 psi, T_wt=491.6880° R, T_i=559.67° R and α=15.0197, we obtain ω_∞=0.043461 lb_m H₂O/lb_m dry air 110.

Example 3

Determine the mass fraction of the ambient air stream 100 to be diverted to the wet passageways 46 to attain the lowest temperature of the conditioned dry air stream 110 in the portable air conditioner 10 given the dry bulb temperature of the incoming ambient air 100 as 100° F. and its relative humidity as 40%.

The mass fraction λ of the ambient air stream 100 to be diverted to the wet passageways 46 to attain the lowest temperature of the conditioned dry air stream 110 in the portable air conditioner 10 is given by Eq. (7) where T_dpi is determined from Eq. (1), ω_∞ is determined from Eq. (2), ω_i is determined from Eq. (5) and h_fg is determined from Eq. (4).

The lowest attainable temperature by the conditioned dry air stream 110 corresponding to the prescribed ambient air temperature and relative humidity is calculated to be T_dpi=531.1° R=71.4° F. in Example 1. The maximum attainable absolute humidity of the wet air stream 120 emerging from the wet passageways 46 is ω_∞=0.043461 lb_m H₂O/lb_m dry air 110 as calculated in Example 2. Also the absolute humidity of the incoming ambient air 100 ω_i=0.016685 lb_m H₂O/lb_m dry air 110 as calculated in Example 1. The latent heat of evaporation of water h_fg needs to be calculated using Eq. (4). Introducing β=1300.26 Btu/lb_m° R, T_i=559.67° R, T_c=1165.11° R into Eq. (4), we obtain h_fg=1017.23 Btu/lb_m.

Finally, introducing c_pa=0.24 Btu/lb_m° R, T_i=559.67° R, T_dpi=531.1° R, ω_∞=0.043461 lb_m H₂O/lb_m dry air 110 ° R, ω_i=0.0166850/lb_m H₂O/lb_m dry air 110 and h_fg=1017.23 Btu/lb_m, we obtain from Eq. (7), λ=0.2522. This means in order to attain the lowest temperature of the conditioned dry air stream 110 in the portable air conditioner 10, 25.22% of the ambient air stream 100 must be diverted to the wet passageways 46.

Example 4

It is required to determine the rate of consumption of liquid water in the air conditioner 10 under conditions of attainment of the lowest conditioned air temperature given the dry bulb temperature of the incoming ambient air 100 as 100° F., its relative humidity as 40% and mass flow rate through the air conditioner 10 as 20 lb_m/min.

The rate of consumption of liquid water {dot over (m)}_w in the portable air conditioner 10 in the comfort cooling mode under conditions of attainment of the lowest conditioned air temperature is given by Eq. (6). Under these conditions, the mass fraction λ of the ambient air 100 diverted to the wet passageways 46 is calculated to be 0.2522 in Example 3. The absolute humidity to) of the wet air 120 exiting the wet passageways 46 is calculated to be ω_∞=0.043461 lb_m H₂O/lb_m dry air 110 in Example 2. The absolute humidity ω_i of the ambient air 100 is calculated to be ω_i=0.016685 lb_m H₂O/lb_m dry air 110. Introducing these values into Eq. (6) together with the prescribed mass flow rate of ambient air 100 {dot over (m)}_a=20 lb_m/min, we obtain the rate of consumption of liquid water as {dot over (m)}_w=0.1351 lb_m/min.

Example 5

It is required to determine the absolute humidity and the lowest temperature of the moist air in humidification mode when the ambient air 100 temperature is 100° F. with relative humidity 0.40 and absolute humidity 0.016685 lb_m H₂O/lb_m dry air 110.

The absolute humidity ω_w and the lowest temperature of the moist air T_dpo in humidification mode can be determined by an iterative process with the aid of Eqs. (8) and (9). As an initiatory step, we assume T_dpo=T_dpi=531.1° R, which was calculated in Example 1. With this assumed value of T_dpo, we obtain ω_w=0.016685 lb_m H₂O/lb_m dry air 110 from Eq. (8) and ω_w=0.025556 lb_m H₂O/lb_m dry air 110 from Eq. (9). Since these two values of ω_w do not match, we progressively assume lower and lower values of T_dpa and calculate the corresponding values of ω_w. This iterative procedure is continued till the two values of ω_w converge. After a few iterations, we find that at T_dpo=538.6° R=78.9° F., the two values of ω_w converge at 0.021613 lb_m H₂O/lb_m dry air 110. Thus the lowest temperature of the wet air 120 T_dpo=78.9° F. and the corresponding absolute humidity of the wet air 120 exiting the air conditioner 10 in humidification mode is ω_w=0.021613 lb_m H₂O/lb_m dry air 110.

Example 6

It is required to determine the rate of consumption of liquid water in humidification mode given the dry bulb temperature of the incoming ambient air 100 as 100° F., its relative humidity as 40% and mass flow rate through the air conditioner 10 as 20 lb_m/min.

The rate of consumption of liquid water in humidification mode can be calculated with the use of Eq. (10). As calculated in Example 1, the absolute humidity of the incoming ambient air 100 corresponding to its dry bulb temperature of T_i=100° F. and relative humidity φ_i=40% is ω_w=0.016685 lb_m H₂O/lb_m dry air 110. Also as calculated in Example, the absolute humidity of the humidified air ω_w=0.021613 lb_m H₂O/lb_m dry air 110. Introducing these values of the absolute humidity together with the prescribed mass flow rate {dot over (m)}_a=20 lb_m/min. into Eq. (10), we obtain the rate of consumption of liquid water in humidification mode {dot over (m)}_w=0.0986 lb_m/min.

In view of the above examples, the subject invention also provides a method of providing conditioned air from the portable air conditioner 10. The method may be used to control operation of the air conditioner 10 to achieve a desired temperature of dry air 110 or humidity of the wet air 120. The method comprises determining an absolute humidity, ω_i, for ambient air 100 having a initial temperature, T_i, and a relative humidity, φ_i, that enters the ambient air 100 inlet 24. Equation (5) is preferably used to determine ω_i. It is to be appreciated that the above examples and equations were solved having the liquid as water and hence the constants reflects those for water. If different liquids or different solutions o are used for the liquid, then the constants may also be different and the subject invention is not intended to be limited to using water as the liquid.

Next, an absolute humidity, ω_∞, is determined for air exiting the wet air outlet 46 based upon T_i; and a lowest obtainable temperature, T_dpi, is determined for air exiting the dry air outlet 26 based upon ω_i. Equations (2) and (1) may be used to calculate GO and T_dpi, respectively. Based upon T_dpi, a predetermined portion of the wet air outlet 46 and the dry air outlet 26 are blocked to divert the ambient air 100 stream into the apertures 48 to provide a desired temperature of the air exiting the dry air outlet 26. It is to be appreciated that the blocking of the outlets 26, 46 may be done automatically or manually.

The method also comprises determining the mass fraction, λ, of the ambient air 100 stream to divert into the wet and dry passageways to achieve the desired temperature, as illustrated in Equation (7). As one example, the position of the sheet valve 52 may be adjusted to block the predetermined portion of the wet air outlet 46 and the dry air outlet 26 to achieve λ and the desired temperature. The air conditioner 10 may include indicators (not shown) that allow for positioning of the sheet valve 52 to achieve the desired outlet temperature based upon the ambient air 100 conditions. Moreover, the air conditioner 10 may include a sensor (not shown), such as a thermocouple, that provides the conditions of the ambient air 100 to allow for adjusting of the air conditioner 10. Additionally, the method may adjust the flow rate of the ambient air 100 into the ambient air inlet 24 to achieve the desired temperature.

While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A portable air conditioner comprising:

a tank for storing a liquid therein;

a plurality of tubes spaced from one another defining an air passageway therebetween having an air inlet and a dry air outlet for dispensing dry air therefrom;

each of said tubes having a first end extending into said tank in fluid communication with the liquid and a second end extending opposite said tank defining a wet air outlet for dispensing wet air therefrom;

at least one fin disposed between adjacent tubes;

a sheet valve sealingly engaging said dry air outlet and said wet air outlet and moveable for adjusting an amount of air flow exiting from said dry air outlet and said wet air outlet; and

at least one aperture defined within each of said tubes between said ends for diverting air flowing through said air passageway into said tubes and exiting through said wet air outlet.

2. A portable air conditioner as set forth in claim 1 further comprising a wicking material disposed within at least one of said tubes and in fluid communication with the liquid such that air flowing into said air inlet transmits energy to said fin and through said tube to evaporate the liquid in said wicking material and increase humidity of air exiting said wet air outlet and cool air exiting said dry air outlet.

3. A portable air conditioner as set forth in claim 1 further comprising a fan module adjacent said air inlet for directing a flow of ambient air though said air passageway.

4. A portable air conditioner as set forth in claim 3 wherein said fan module is further defined as an axial fan.

5. A portable air conditioner as set forth in claim 3 further comprising a power supply for operating said fan module.

6. A portable air conditioner as set forth in claim 5 wherein said power supply is further defined as a battery.

7. A portable air conditioner as set forth in claim 5 wherein said power supply is further defined as a solar panel comprising a plurality of solar cells.

8. A portable air conditioner as set forth in claim 1 further comprising an adjustment mechanism operatively connected to said sheet valve for moving said sheet valve.

9. A portable air conditioner as set forth in claim 1 further comprising a cartridge disposed adjacent at least one of said dry air outlet and said wet air outlet.

10. A portable air conditioner as set forth in claim 9 further comprising a cartridge slot for receiving said cartridge.

11. A portable air conditioner as set forth in claim 9 wherein said cartridge is further defined as an aroma filter.

12. A portable air conditioner as set forth in claim 1 wherein said fin is further defined as a louvered fin for allowing air to pass vertically through said air passageway.

13. A portable air conditioner as set forth in claim 1 further comprising at least one first flow plate disposed between said tubes and adjacent said second ends for sealing said air passageway.

14. A portable air conditioner as set forth in claim 13 further comprising at least one second flow plate disposed adjacent said dry air outlet for sealing said tubes.

15. A portable air conditioner as set forth in claim 1 wherein said tank further comprises a liquid inlet for refilling said tank with the liquid.

16. A portable air conditioner comprising:

a tank for storing a liquid therein;

a plurality of tubes spaced from one another defining an air passageway therebetween having an air inlet and a dry air outlet for dispensing dry air therefrom each of said tubes having a first end extending into said tank in fluid communication with the liquid and a second end extending opposite said tank defining a wet air outlet for dispensing wet air therefrom;

at least one fin disposed between adjacent tubes;

at least one aperture defined within each of said tubes between said ends for diverting air flowing through said air passageway into said tubes and exiting through said wet air outlet; and

a wicking material disposed within at least one of said tubes and in fluid communication with the liquid such that air flowing into said air inlet transmits energy to said fin and through said tube to evaporate the liquid in said wicking material and increase humidity of air exiting said wet air outlet and cool air exiting said dry air outlet.

17. A portable air conditioner as set forth in claim 16 further comprising a sheet valve sealingly engaging said dry air outlet and said wet air outlet and moveable for adjusting an amount of air flow exiting from said dry air outlet and said wet air outlet.

18. A portable air conditioner as set forth in claim 17 further comprising an adjustment mechanism operatively connected to said sheet valve for moving said sheet valve.

19. A portable air conditioner as set forth in claim 17 further comprising a fan module adjacent said air inlet for directing a flow of air though said air passageway.

20. A portable air conditioner as set forth in claim 16 wherein said wicking material is further defined as a fibrous material.

21. A method of providing conditioned air from a portable air conditioner having a tank storing a liquid therein, a plurality of tubes defining an ambient air inlet and a dry air passageway between adjacent tubes and defining at least one aperture to allow air to enter inside of the tube defining a wet air passageway, and a sheet valve sealingly engaging a dry air outlet and a wet air outlet, said method comprising:

determining an absolute humidity, ωi, for ambient air having a initial temperature, Ti, and a relative humidity, φi, that enters the ambient air inlet;

determining an absolute humidity, ω∞, for air exiting the wet air outlet based upon Ti;

determining a lowest obtainable temperature, Tdpi, for air exiting the dry air outlet based upon ωi; and

blocking a predetermined portion of the wet air outlet and the dry air outlet to divert the ambient air stream into the apertures to provide a desired temperature of the air exiting the dry air outlet based upon Tdpi.

22. A method as set forth in claim 21 further comprising determining a mass fraction, λ, of the ambient air stream to divert into the wet and dry passageways to achieve the desired temperature.

23. A method as set forth in claim 22 further comprising adjusting a position of the sheet valve to block the predetermined portion of the wet air outlet and the dry air outlet to achieve λ and the desired temperature.

24. A method as set forth in claim 22 wherein the step of determining λ is based upon the following equation: λ = c pa ⁡ ( T i - T dpi ) ( ω ∞ - ω i ) ⁢ h fg

wherein cpa is the isobaric specific heat of air, Btu/lbm° R, and

hfg is the latent heat of evaporation of the liquid.

25. A method as set forth in claim 24 wherein hfg is based upon the following equation: h fg = β ⁡ ( 1 - T i T c ) 3 / 8  

wherein β is a constant=1300.26 Btu/lbm, and

Tc is the critical temperature of the liquid.

26. A method as set forth in claim 22 further comprising adjusting a flow rate of the ambient air into the ambient air inlet to achieve the desired temperature.

27. A method as set forth in claim 21 wherein the step of determining as is based upon the following equation: ω i = ( M w / M a ) ⁢ ϕ i ( P amb / P wt ) ⁢ exp ⁢ { α ⁡ [ ( T wt / T i ) 4 / 3 - 1 ] } - ϕ i

wherein Twt is the triple point temperature of the liquid,

Pwt is the triple point pressure of the liquid,

Pamb is the atmospheric pressure,

Ma is the molecular weight of ambient air,

Mw is the molecular weight of the liquid, and

α is a dimensionless constant=15.0197.

28. A method as set forth in claim 21 wherein the step of determining ω∞ is based upon the following equation: ω ∞ = M w / M a ( P amb / P wt ) ⁢ exp ⁢ { α ⁡ [ ( T wt / T i ) 4 / 3 - 1 ] } - 1

wherein Twt is the triple point temperature of the liquid,

Pwt is the triple point pressure of the liquid,

Pamb is the atmospheric pressure,

Ma is the molecular weight of ambient air,

Mw is the molecular weight of the liquid, and

α is a dimensionless constant=15.0197.

29. A method as set forth in claim 21 wherein the step of determining Tdpi is based upon the following equation: T dpi - T wt ⁢ { 1 - 1 α ⁢ 1 ⁢ n [ ω i ⁢ P amb / P wt ω i + M w / M a ] } - 3 / 4

wherein Twt is the triple point temperature of the liquid,

Pwt is the triple point pressure of the liquid,

Pamb is the atmospheric pressure,

Ma is the molecular weight of ambient air,

Mwt is the molecular weight of the liquid, and

α is a dimensionless constant=15.0197.