Lightweight portable moisture traps for use with vacuum pumps

A portable moisture trap for use with a vacuum pump includes: a housing; a cooling chamber positioned at least partially within the housing including a first inlet port and a second outlet port; a lid that sealably attaches to a top portion of the cooling chamber to seal the cooling chamber; a heat sink residing under the cooling chamber; a thermoelectric device having an upper cooling side and a lower heat generating side residing between the cooling chamber and the heat sink; a fan oriented to blow air upwardly toward the heat sink; and a baffle extending downwardly in the cooling chamber from a location proximate the lid to a location proximate an inner bottom surface of the cooling chamber, with the baffle configured to define a physical barrier to urge air received through the first port to flow down toward the inner bottom surface of the cooling chamber before exiting through the second port, to thereby remove moisture from air traveling through the cooling chamber in response to a vacuum pump in fluid communication with the second port.

FIELD OF THE INVENTION

This invention relates to moisture traps, and more particularly to lightweight portable moisture traps for use with vacuum pumps.

BACKGROUND

It is sometimes necessary to evacuate moist air from equipment such as chambers or vessels. For example, a vacuum pump can be used to evacuate air from a chamber containing a moist or wet object. However, if moist air is pulled into a vacuum pump, it can negatively impact the efficiency of the pump and reduce the lifetime of the pump.

In the construction industry, vacuum pumps can be used in the testing of paving materials. By way of example, compacted asphalt samples are tested using ASTM Test D2726, ASTM Test D6752, and AASHTO Test T166. These tests require the determination of the density of the materials. This requires that the dry mass of a sample along with a sample volume be determined in order to calculate the density, which is the ratio of the mass to the volume. Moisture may be introduced into the sample by the cutting process or may be naturally present in the sample. As described in U.S. Patent Application Publication No. 2005/0102851, the disclosure of which is incorporated by reference herein in its entirety, a vacuum pump can be used to remove moisture from a chamber holding the sample to thereby dry the sample.

By way of further example, vacuum pumps can be used in tests to determine the maximum specific gravity and density of bituminous paving mixtures, such as the tests described in ASTM Test D2041 and AASHTO Test T209. In these tests, a sample of known dry weight is placed in a vessel. Water is then introduced into the vessel to submerge the sample, and the vacuum pump evacuates air to reduce the pressure in the vessel. The volume of the sample is then determined, and the density or specific gravity of the sample can be determined based on the dry weight and the volume of the sample.

As seen from these examples, the vacuum pump may evacuate moist air from the chamber or vessel. The evacuated moist air will enter the vacuum pump unless it is dried prior to reaching the pump. Vacuum pumps use lubricants (e.g., oil) to reduce friction between moving parts and to protect seals. However, when moisture enters the vacuum pump, the moisture mixes with the oil and reduces its effectiveness. Thus, moisture will eventually destroy the vacuum pump. Frequent oil changes may prolong the life of the pump, but the oil changes can frustrate the user by increasing cost and creating downtime, and can also produce considerable waste.

Therefore, users sometimes attempt to dry the air before it enters the pump. Indeed, the aforementioned ASTM Test D2041 and AASHTO Test T209 require the use of one or more in-line dryers to reduce moisture entering the vacuum pump. Current practice is to use one or more desiccant air dryers positioned between the equipment containing moist air and the vacuum pump.

However, there are numerous drawbacks to the use of presently used in-line dryers, such as desiccant dryers. First, desiccant dryers can introduce considerable air flow resistance, thereby increasing the power consumed by the vacuum pump and decreasing its efficiency.

Moreover, desiccant dryers can be inefficient with regard to their moisture-removing characteristics. The dryers tend to be most efficient when the desiccants are dry. Thus, the dryers will either lose their efficiency during use or will create downtime while waiting for the desiccants to dry. The dryers could be replaced or recycled during use, but this increases cost and also creates downtime.

Desiccant dryers have a limited lifetime, and need to be replaced or recycled periodically. Again, this increases cost and creates downtime. The continual replacement also produces waste. Furthermore, a user may neglect to timely replace the dryers, which can decrease the efficiency and reduce the life of the vacuum pump.

Thus, the current use of desiccant dryers can be environmentally unfriendly. The dryers increase air flow resistance and can allow moisture into the vacuum pump, which can increase the necessary power consumed by the pump. Moisture entering the pump also reduces the efficiency of the lubricant or oil in the pump, necessitating an increased number of waste-creating oil changes. Finally, because the desiccant dryers inevitably allow moisture to enter the vacuum pump, the life of the vacuum pump is decreased, sometimes substantially. The result can be the early disposal and replacement of pumps.

Therefore, there may be a need for an apparatus that will effectively dry air evacuated from equipment before the air enters the vacuum pump, and will do so without overly restricting air flow. There may be a need for an apparatus that will perform effective drying continuously to minimize downtime. Finally, there may be a need for an environmentally friendly solution that can increase the lifetime of vacuum pumps and generally reduce waste.

SUMMARY

As a first aspect, a portable moisture trap for use with a vacuum pump includes: a housing; a cooling chamber positioned at least partially within the housing including a first inlet port and a second outlet port; a lid that sealably attaches to a top portion of the cooling chamber to seal the cooling chamber; a heat sink residing under the cooling chamber; a thermoelectric device having an upper cooling side and a lower heat generating side residing between the cooling chamber and the heat sink; a fan residing under the heat sink, the fan being oriented to blow air upwardly toward the heat sink; and a baffle extending downwardly in the cooling chamber from a location proximate the lid to a location proximate an inner bottom surface of the cooling chamber. The thermoelectric device is in thermal communication with the cooling chamber and oriented so that the cooling side faces the cooling chamber and the heat generating side faces and is in thermal communication with the heat sink. The baffle is configured to define a physical barrier to urge air received through the first port to flow down toward the inner bottom surface of the cooling chamber before exiting through the second port, to thereby remove moisture from air traveling through the cooling chamber in response to a vacuum pump in fluid communication with the second port.

In some embodiments, the baffle includes a plate that extends across the cooling chamber so that the first port is on one side of the plate and the second port is on the other side of the plate. The plate has a bottom edge with alternating downward projections and valleys that resides proximate the inner bottom surface of the cooling chamber.

As a second aspect, a method of determining the maximum specific gravity or density of a sample of paving mixture includes: providing a portable moisture trap in a fluid path connecting a vessel adapted to hold a test sample and a vacuum pump, wherein the portable moisture trap includes a cooling chamber having a first port connected to the vessel and a second port connected to the vacuum pump, and wherein the portable moisture trap further includes a thermoelectric device; cooling the cooling chamber of the portable moisture trap using the thermoelectric device; weighing the test sample to determine a dry mass of the sample; placing the test sample in the vessel; adding water to the vessel to submerge the test sample; then evacuating moist air from the vessel while the test sample is submerged using the vacuum pump; then determining a volume of the test sample; and calculating the density and/or the maximum specific gravity of the test sample using the determined dry mass and the determined volume of the sample. The evacuating step is carried out by: flowing the moist air from the vessel through the first port of the cooling chamber; then removing moisture from the moist air in the cooling chamber; and then flowing substantially dry air through the second port of the cooling chamber toward the vacuum pump.

In some embodiments, determining the volume of the sample includes: submerging the vessel with the test sample in a water bath; and determining an underwater weight of the test sample. In some other embodiments, determining the volume of the sample includes: filling a known volume vessel with the sample and water; and weighing the filled vessel in air.

In some embodiments, the cooling chamber includes a baffle extending downwardly in the cooling chamber from a location proximate a lid to a location proximate an inner bottom surface of the cooling chamber. The step of removing moisture from the moist air in the cooling chamber includes urging moist air down toward the inner bottom surface of the cooling chamber. In some embodiments, the baffle includes a plate that extends across the cooling chamber so that the first port is on one side of the plate and the second port is on the other side of the plate, wherein the plate has a bottom edge with alternating downward projections and valleys that resides proximate the inner bottom surface of the cooling chamber. The step of removing moisture from the moist air in the cooling chamber includes flowing moist air through the valleys of the baffle.

As a third aspect, a system for evaluating test samples includes: a chamber containing moist air and adapted to hold a loose aggregate or compacted asphalt sample; a vacuum pump in fluid communication with the chamber to evacuate moist air from the chamber; a fluid path connecting the chamber and the vacuum pump; and a portable moisture trap positioned in the fluid path to remove moisture from the evacuated air. The portable moisture trap includes: a housing; a cooling chamber at least partially within the housing including a first port and a second port; a lid that sealably attaches to a top portion of the cooling chamber to seal the cooling chamber; a heat sink residing under the cooling chamber; a thermoelectric device having an upper cooling side and a lower heat generating side residing between the cooling chamber and the heat sink; a fan residing under the heat sink and oriented to blow air upwardly to remove heat from the heat sink; and a baffle extending downwardly in the cooling chamber from a location proximate the lid to a location proximate an inner bottom surface of the cooling chamber. The thermoelectric device is in thermal communication with the cooling chamber and oriented so that the cooling side faces the cooling chamber and the heat generating side faces and is in thermal communication with the heat sink. The baffle is configured to define a physical barrier to urge air received through the first port to flow down toward the inner bottom surface of the cooling chamber before exiting through the second port. In operation and in response to operation of the vacuum pump, moist air flows from the chamber through the first port of the cooling chamber, down and adjacent the inner bottom surface of the cooling chamber to remove moisture from the moist air, and substantially dry air flows through the second port of the cooling chamber to the vacuum pump.

In some embodiments, the baffle includes a plate that extends across the cooling chamber so that the first port is on one side of the plate and the second port is on the other side of the plate. The plate has a bottom edge with alternating downward projections and valleys that resides proximate the inner bottom surface of the cooling chamber. In operation, moist air flows through the valleys and adjacent the inner bottom surface of the cooling chamber to remove moisture from the moist air.

As a fourth aspect, a system for drying a compacted asphalt sample includes: a sealable chamber including an interior to house the compacted asphalt sample; a first valve in communication with a first port of the chamber; a second valve in communication with a second port of the chamber; a vacuum pump in communication with the chamber to evacuate air from the interior of the chamber through the second port of the chamber; a fluid path connecting the chamber and the vacuum pump; a portable moisture trap positioned in the fluid path to remove moisture from the evacuated air including a cooling chamber having a first port in fluid communication with the chamber and a second port in fluid communication with the vacuum pump and also including a thermoelectric device to cool the cooling chamber; and a controller. The controller is configured to: open and close the first and second valves; operate the vacuum pump; operate the thermoelectric device of the portable moisture trap; cycle the system between a first mode and a second mode, wherein during the first mode the first valve is closed, the second valve is open, and the vacuum pump is operated such that the vacuum pump evacuates air from the interior of the chamber, through the second port of the chamber, through the portable moisture trap, and to the vacuum pump, and wherein during the second mode the first valve is open and air is supplied through the first port of the chamber to the interior of the chamber; and monitor vacuum pressure in the interior of the chamber until the pressure drops below 10 TORR. In operation during the first mode, moist air flows through the second port of the chamber, through the first port of the cooling chamber of the moisture trap and adjacent an inner bottom surface of the cooling chamber to remove moisture from the moist air such that substantially dry air flows through the second port of the cooling chamber of the moisture trap and to the vacuum pump.

In some embodiments, the portable moisture trap includes a solid metal baffle with a bottom edge having alternating projections and valleys adjacent the inner bottom surface of the cooling chamber. In operation during the first mode, moist air flows through the valleys and adjacent the inner bottom surface of the cooling chamber to remove moisture from the moist air.

It is noted that any one or more aspects or features described with respect to one embodiment may be incorporated in a different embodiment although not specifically described relative thereto. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination. Applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to be able to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner. These and other objects and/or aspects of the present invention are explained in detail in the specification set forth below.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In the drawings, the thickness of lines, layers, features, components and/or regions may be exaggerated for clarity and broken lines (such as those shown in circuit of flow diagrams) illustrate optional features or operations, unless specified otherwise. In addition, the sequence of operations (or steps) is not limited to the order presented in the claims unless specifically indicated otherwise.

It will be understood that when a feature, such as a layer, region or substrate, is referred to as being “on” another feature or element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another feature or element, there are no intervening elements present. It will also be understood that, when a feature or element is referred to as being “connected” or “coupled” to another feature or element, it can be directly connected to the other element or intervening elements may be present. In contrast, when a feature or element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. Although described or shown with respect to one embodiment, the features so described or shown can apply to other embodiments.

As used herein, the term “housing” means one or more panels generally defining an outer structure relative to one or more components of a moisture trap. The housing can include panels such as sidewalls and/or a top portion, but these panels need not fully enclose any components. As used herein, the term “in the housing” means that sidewall panels generally surround a component but are not necessarily in contact with the component.

FIG. 1illustrates a moisture trap10according to some embodiments of the invention. The moisture trap10includes a housing12. A cooling chamber14is positioned at least partially in the housing12. In some embodiments, the cooling chamber14is held by the housing12. The housing12includes a top portion12thaving an aperture16through which the cooling chamber14can be accessed. An open top portion14tof the cooling chamber14can be located within the housing12, can be substantially flush with the top portion12tof the housing12, or can extend through the aperture16and through the top portion12tof the housing12.

FIG. 2illustrates certain components of the moisture trap10with the housing12removed according to some embodiments of the invention. The cooling chamber14includes a first port18and a second port20. As illustrated, the first port18extends through a first side or sidewall141of the cooling chamber14and the second port20extends through an opposing second side or sidewall142of the cooling chamber14. As will be described in more detail below, connectors18′,20′ (FIGS. 1,3A-3C,5and6) may extend from the ports18,20(e.g., the connectors18′,20′ may extend outside the housing12).

The moisture trap10includes a cover or lid22to cover the open top portion14tof the cooling chamber14. The lid22is configured to pivotably or sealably connect to the top portion14tof the cooling chamber14. In position, the lid22can provide an airtight seal over the top portion14tof the cooling chamber14. In some embodiments, the lid22includes a gasket22gto sealably connect to the top portion14tof the cooling chamber14. In some embodiments, the lid22includes an optically translucent or transparent material and is configured to allow a user to view the interior of the cooling chamber14.

A thermoelectric device24resides under the cooling chamber14. In some embodiments, the thermoelectric device24is positioned in the housing12. As understood by those of ordinary skill in the art, thermoelectric devices (also known as Peltier devices) can be activated by a voltage supply to create opposing heat generating and cooling sides. Exemplary thermoelectric devices are available from TE Technology, Inc. in Traverse City, Mich. In the illustrated embodiment, the thermoelectric device24includes an upper cooling side24cand a lower heat generating side24h. The thermoelectric device24is in thermal communication with the cooling chamber14and oriented so that the cooling side24cfaces the cooling chamber14.

The moisture trap10also includes a heat sink26residing under the thermoelectric device24. In some embodiments, the heat sink26is positioned at least partially in the housing12. The thermoelectric device24is positioned between the cooling chamber14and the heat sink26. The heat generating side24hof the thermoelectric device24faces and is in thermal communication with the heat sink26. More particularly, the heat generating side24hof the thermoelectric device24can be in contact with an upper surface of the heat sink26. In some embodiments, the heat sink26includes elongated downwardly extending fins28. As understood by those of skill in the art, the fins28provide increased surface area and can facilitate heat transfer.

A fan30is configured to remove heat from the heat sink26. In some embodiments, the fan30is positioned at least partially in the housing12. As illustrated, the fan30resides below the heat sink26and is oriented in a substantially horizontal configuration and is configured to blow air upwardly toward the heat sink26and/or the elongated fins28. The fan30may be attached to a bracket31(for example, with bolts, rods, or the like), and the bracket31may be attached to the housing12. The bracket31may include an aperture31a(FIG. 1) through which air may flow. It is noted that the bracket is optional and the fan30may be situated under the heat sink26in other ways (for example, the fan30may be directly mounted to the housing12). It is further noted that the fan need not be in a horizontal configuration. For example, the fan may be oriented vertically, or at any angle between horizontal and vertical, and duct work may direct air flow toward the heat sink26and/or the elongated fins28.

In some embodiments, the housing12includes a sidewall having a cutaway12c(FIG. 1). The cutaway12chas a size sufficient to expose at least a major portion of a length of the downwardly extending fins28to environmental conditions. The cutaway12ccan improve airflow and enhance heat transfer away from the heat sink26.

The cutaway12ccan also allow for sufficient intake of environmental air to the fan30. Additionally or alternatively, sidewalls of the housing12can include apertures80(FIGS. 1 and 6) can allow for sufficient intake of air to the fan30.

As understood by those of skill in the art, the temperature of the cooling side24cof the thermoelectric device24decreases as more heat is dissipated from the heat generating side24hof the thermoelectric device24. Therefore, as the heat generating side24his in thermal communication with the heat sink26, increased heat transfer away from the heat sink26will result a colder cooling side24cof the thermoelectric device24.

The moisture trap10includes a baffle configured define a physical barrier to urge air received from one of the ports18,20to flow down toward the inner bottom surface34of the cooling chamber14before exiting through the other of the ports18,20, as will be described in more detail below. The baffle may comprise piping, mesh material, one or more plates, or one or more chambers within the interior of the cooling chamber14.

FIG. 3Ais a top view of the moisture trap10according to some embodiments of the invention. As illustrated, a baffle32extends downwardly in the cooling chamber14from a location proximate the lid22(or the top portion14tof the chamber14) to a location proximate an inner bottom surface34of the cooling chamber14. The baffle32can be a plate sized and configured to extend across the cooling chamber14such that the first port18is on one side of the baffle32and the second port20is on the opposite side of the baffle32. In some embodiments, the baffle32may contact opposing corners or sidewalls of the cooling chamber14.

The cooling chamber14can be substantially square or rectangular. The first and second sides or sidewalls141,142of the cooling chamber14can be substantially parallel. The cooling chamber can include third and fourth sides or sidewalls143,144attached to the first and second sides141,142, and the third and fourth sidewalls143,144can be substantially parallel. The first port18may extend through one sidewall and the second port20may extend through an opposing sidewall. For example, as illustrated inFIG. 3A, the first port18may extend through the first sidewall141of the cooling chamber14and the second port20may extend through the opposing second sidewall142of the cooling chamber.

As illustrated inFIG. 3A, the baffle32may extend diagonally across the cooling chamber14and contact opposing corners or sidewalls. As illustrated, the baffle32extends from or adjacent a corner defined by sidewalls141,143to or adjacent a corner defined by sidewalls142,144. In some other embodiments, the baffle32may extend diagonally from or adjacent a corner defined by sidewalls141,144to or adjacent a corner defined by sidewalls142,143. In any event, the baffle32can be sized and configured to fit within the cooling chamber14such that the first port18is on one side of the baffle32and the second port20is on the opposite side of the baffle32.

FIGS. 3B and 3Care top views illustrating port and baffle configurations according to some other embodiments of the invention. For example, the first and second ports18,20may extend through the same sidewall of the cooling chamber14as illustrated inFIG. 3B. In the illustrated embodiment, the first and second ports18,20extend through the first sidewall141and the baffle32is sized and configured to extend across the cooling chamber14and contact opposing sidewalls141,142such that the first port18is on one side of the baffle32and the second port20is on the opposite side of the baffle32. The ports18,20can also both extend through any of sidewalls142,143,144, and the baffle32can be sized and configured to contact opposing sidewalls such that the first port18is on one side of the baffle32and the second port20is on the opposite side of the baffle32.

In some other embodiments, the first port18may extend through one sidewall of the cooling chamber14and the second port20may extend through an adjacent sidewall of the cooling chamber14. As illustrated inFIG. 3C, the first port18may extend through the first sidewall141of the cooling chamber and the second port20may extend through the adjacent third sidewall143of the cooling chamber14(it will be understood that the ports18,20may extend through any adjacent sidewalls). As illustrated and as described above in reference toFIG. 3A, the baffle32can extend diagonally across the cooling chamber14and can be sized and configured to fit within the cooling chamber14such that the first port18is on one side of the baffle32and the second port20is on the opposite side of the baffle32.

It will be understood that the ports18,20may be at the same or substantially the same vertical level or elevation (e.g., relative to the ground or the inner bottom surface34of the cooling chamber14), or may be at different vertical levels or elevations.

It will further be understood that, although not illustrated, one or both of the ports18,20may extend through the top of the cooling chamber14(e.g., through or adjacent the lid22) and/or one or both of the ports18,20may extend through the bottom of the cooling chamber14(e.g., through the inner and/or outer bottom surfaces34,42).

FIG. 4is a side view of the baffle32according to some embodiments of the invention. The baffle32has a bottom edge32bwith alternating downward projections35and valleys36(i.e., openings between the projections). At least some of the projections35(and perhaps all of the projections35, or all of the projections35aside from the outermost projections35) can have a width35wof about 1 inch. At least some of the valleys36(and perhaps all of the valleys36) can have a width36wof about 0.47 inches. At least some of the valleys36(and perhaps all of the valleys36) can have a height36hof about 0.35 inches.

The baffle32can be slidably inserted into the interior of the cooling chamber14, as shown inFIGS. 3A-3C. When inserted, the bottom edge32bof the baffle32resides proximate the inner bottom surface34of the cooling chamber14. Opposing sides32sof the baffle and/or interior corners14cof the cooling chamber14may be rounded to facilitate insertion of the baffle32into the chamber14. In some other embodiments, the interior of the chamber14may include grooves (not shown) to facilitate insertion of the baffle32. Alternatively, the baffle32may be integrated with the interior of the chamber14. The baffle32may be a corrosion-resistant metal plate (e.g., aluminum or stainless steel) and may have a thickness of between about 0.032 inches to about 0.25 inches.

Referring again toFIG. 2, in some embodiments, the moisture trap10may include a spacer block40positioned between the cooling side24cof the thermoelectric device24and an outer bottom surface42of the cooling chamber14. As will be described in more detail below, the spacer block40can be used on top of the thermoelectric device24to help isolate the cooling chamber14from the heat generating side24hof the thermoelectric device24. Furthermore, as will be described in more detail below, insulation can be placed proximate the spacer block40to help further isolate the cooling chamber14from the heat generating side24hof the thermoelectric device24and/or the heat sink26.

Therefore, in some embodiments, the heat sink26, the thermoelectric device24, the spacer block40, and the cooling chamber14can comprise a stackable assembly as illustrated. The assembly or stack can be tightened together firmly to attain good surface-to-surface contact and enhance thermal transfer. The cooling chamber14may be firmly attached to the spacer block40in a manner known to those of ordinary skill in the art. By way of example, one or more fasteners41(e.g., screws) may penetrate through the chamber14, spacer block40, and into apertures (e.g., threaded apertures) in the heat sink26(FIG. 3A). Vacuum sealing washers43may also be used as illustrated (FIG. 3A). Moreover, thermally conductive paste and/or film may be applied or positioned between the heat sink26and the heat generating side24hof the thermoelectric device24, between the cooling side24cof the thermoelectric device24and a bottom surface40bof the spacer block40, and/or between an top surface40tof the spacer block40and the outer bottom surface42of the cooling chamber14to further enhance thermal transfer. Exemplary foil is available from Graphite Foil Fabricators Corp. in Plantsville, Conn. Exemplary paste is available from Arctic Silver Corp. in Visalia, Calif.

As illustrated inFIG. 2, the thermoelectric device24can have a cross-sectional area that is less than a cross-sectional area of the spacer block40, and the thermoelectric device24can have a thickness that is less than a thickness of the spacer block40. Also as illustrated, the spacer block40can have a cross-sectional area that is less than a cross-sectional area of the cooling chamber14(i.e., the area of the outer bottom surface42of the cooling chamber14). In some embodiments, the thermoelectric device24is substantially centered above the heat sink26, the spacer block40is substantially centered above the thermoelectric device24, and/or the cooling chamber14is substantially centered above the spacer block40.

The thermoelectric device24can have a surface area (e.g., on the cooling side24c) that is less than about 2.5 square inches and can be less than about 0.25 inches thick (or, in some embodiments, less than about 0.15 inches thick). The spacer block40can have a surface area (e.g., on the bottom surface40b) that is less than about 4 square inches and can be less than about 0.75 inches thick (or, in some embodiments, less than about 0.5 inches thick). The outer bottom surface42of the cooling chamber14can have a surface area of less than about 15 square inches. More particularly, the cooling chamber14can have cross-sectional dimensions of about 4 inches by about 3.5 inches. The cooling chamber14can have a height of between about 1 inch to about 5 inches. Thus, the cooling chamber14can have an internal volume of about 14 cubic inches to about 70 cubic inches. These relatively small component dimensions allow for a lightweight and portable design, as described in more detail below.

A first insulating material46can snugly surround downwardly extending perimeter sides44of the spacer block40. In some embodiments, the insulating material46is a gasket, with an upper portion of the gasket46directly contacting the outer bottom surface42of the cooling chamber14and a lower portion of the gasket46directly contacting an upper surface of the heat sink26. The insulating material46can be foam rubber, such as polyurethane foam, foam rubber latex, and the like. In the illustrated embodiment, the spacer block40has a larger surface area than the thermoelectric device24, thereby forming gaps or spaces52between the spacer block40and the heat sink26. The insulating material or gasket46can be formed to fill the gaps52. Alternatively, the gaps52may remain open or may be filled with additional insulating material.

The first insulating material46can further thermally isolate the cooling chamber14from the heat generating side14hof the thermoelectric device24and the heat sink26. In some embodiments, the insulating material46contacts the outer bottom surface42of the cooling chamber14and extends outwardly to the first and second sides or sidewalls141,142and/or to the third and fourth sides or sidewalls143,144of the cooling chamber14. In this regard, the spacer block40and the insulating material46can serve to help thermally isolate the outer bottom surface42of the cooling chamber14from the thermoelectric device24and the heat sink26. In some embodiments, the insulating material46is less than about 3 inches thick and, in some embodiments, less than about 2.5 inches thick.

As seen inFIG. 3A, the cooling chamber14can be spaced apart from sidewalls of the housing12. In some embodiments, the heat sink26has a larger surface area than the surface area of the outer bottom surface42of the cooling chamber14. For example, the heat sink26may extend proximate sidewalls of the housing12. Therefore, it may be desirable to further insulate the cooling chamber14from the exposed portions of the heat sink26(e.g., those portions not thermally isolated from the cooling chamber14by the first insulating material46).

FIG. 5illustrates the moisture trap10with the top portion12tof the housing12removed according to some embodiments. A second insulating material54can be positioned between the first and second sidewalls141,142of the cooling chamber14and the housing12. The second insulating material54may be the same as the first insulating material46or may be different. In some embodiments, the second insulating material54comprises fiberglass. The second insulating material54can extend downwardly along the entire first and second sidewalls141,142of the cooling chamber14and, in some embodiments, can extend downwardly to the upper surface of the heat sink26. The second insulating material54may be about 1 inch thick (and therefore the space between the first and second sidewalls141,142of the cooling chamber14and the housing12may be about 1 inch). The second insulating material54can include apertures56through which the first and second connectors18′,20′ extend.

A third insulating material58can be positioned between the third and fourth sidewalls143,144of the cooling chamber14and the housing12. The third insulating material58may be the same or different from the first insulating material46and/or the second insulating material54. In some embodiments, the third insulating58material comprises foam rubber, such as polyurethane foam, foam rubber latex, and the like. The third insulating material58can be adhesively attached to the third and fourth sidewalls143,144of the cooling chamber14. The third insulating material58can extend downwardly along the entire third and fourth sidewalls143,144of the cooling chamber14and, in some embodiments, can extend downwardly to the upper surface of the heat sink26. The third insulating material58may be about 1 inch thick (and therefore the space between the third and fourth sidewalls143,144of the cooling chamber14and the housing12may be about 1 inch). The third insulating material58can include apertures (not shown) through which the first and second connectors18′,20′ may extend.

FIG. 6is a rear perspective view of the moisture trap10. A power supply box60can be attached to the housing12(in some embodiments, the box60may be integrated with the housing12). The box60can house a power adapter62(FIG. 5) to convert AC power to DC power. For example, the adapter62may convert about 120 volts AC to about 15 volts DC. A power cord64(FIG. 1) can supply AC power to the moisture trap10. The power cord64can run into the box60to supply AC power to the adapter62; for example, the cord64may run adjacent the fan30and into the box60. DC power from the power adapter62can be used to supply power to the thermoelectric device24and/or to the fan30. The box60can include an aperture66to provide air to a fan68to cool the power adapter62and its associated components. The fan68may be integrated with the power adapter62or may be a separate component. The box60can include apertures70,72for additional cooling and/or air flow. The adapter62can be positioned in the box60such that it is spaced apart from the housing12. This space can serve to thermally isolate the adapter62from the heat sink26and other components of the moisture trap10. In some embodiments, the adapter62may be spaced at least about 0.1875 inches from the housing12.

Referring toFIG. 5, in some embodiments, there may be a gap74between the insulating material58and the housing12adjacent the power supply box60. The gap74may allow air from the fan30to pass through the heat sink26, up along the housing12and through apertures76,78in the housing12(FIG. 6). In this regard, the gap74and apertures76,78can help dissipate additional heat from the heat sink26, thereby allowing for a colder cooling side24cof the thermoelectric device24and in turn a colder cooling chamber14. Moreover, the gap74can thermally isolate the box60and the power adapter62from the heat sink26and other components of the moisture trap10. Where used, the gap74will typically have a thickness of less than about 0.50 inches.

As described above, the moisture trap10can include connectors18′,20′ (FIGS. 1,3A-3C,5and6). The connectors18′,20′ may connect with, extend through, and/or be integrated with respective ports18,20of the cooling chamber14. The connectors18′,20′ may extend outside the housing12and allow for other components or equipment to connect with the moisture trap10. The housing12may include apertures82(FIGS. 1 and 6) substantially aligned with the ports18,20of the cooling chamber14, with the connectors18′,20′ extending through the apertures. The connectors18′,20′ may include hose connections such as, for example, ½ inch, 7/16 inch, or ⅜ inch hose connections.

The moisture trap10is configured to be used in combination with a vacuum pump and equipment from which moist air is evacuated. For example, a vessel containing a wet or moist test sample can be connected to the moisture trap10at the port18or the connector18′ and a vacuum pump can be connected to the moisture trap10at the port20or the connector20′. In some embodiments, the moisture trap10is configured to be used in combination with a vacuum pump having a flow rate of between about 40 liters per minute to about 200 liters per minute.

This is illustrated inFIG. 7. A chamber or vessel100includes a test sample102. The test sample102may be compacted asphalt or loose asphalt mixture, for example. The chamber100may include liquid104(e.g., water), which may submerge the test sample102. The vessel100may include vapor106(e.g., water vapor). A fluid path150connects the chamber100and a vacuum pump200. The portable moisture trap10is positioned in the fluid path150. For example, the fluid path150may comprise a hose or pipe fluidly connecting the chamber100and the moisture trap10(e.g., at connector18′), and may also comprise a hose or pipe fluidly connecting the vacuum pump200and the moisture trap (e.g., at connector20′).

In operation, the lid22is sealably attached to the top portion14tof the cooling chamber14and power is supplied to the moisture trap10. Power will activate the thermoelectric device24. The cooling side24cof the thermoelectric device24cools the cooling chamber14. Heat generated by the heat generating side24hof the thermoelectric device is transferred to the heat sink26. Heat is removed from the heat sink26using the fan30. As more heat is removed from the heat sink26, more heat is transferred from the heat generating side24hof the thermoelectric device24, and as a result the temperature of the cooling side24cof the thermoelectric device24decreases and accordingly the temperature of the cooling chamber14also decreases.

The cooling chamber14is thermally isolated from the heat generating side24hof the thermoelectric device24and the heat sink26by the spacer block40, and by the use of insulating materials46,54, and58. This thermal isolation allows the cooling chamber14to become increasingly cold even as the heat generating side24hof the thermoelectric device24and the heat sink26dissipate more and more heat.

In particular, the inner and outer bottom surfaces34,42of the cooling chamber14and the sidewalls141,142,143,144of the cooling chamber14become increasingly cold after applying power to the moisture trap10. After a certain amount of time, the temperature of the cooling chamber14reaches steady state. In some embodiments, the cooling chamber14reaches a steady state temperature of about 32 degrees Fahrenheit at about 70 degrees Fahrenheit ambient in less than about 15 minutes.

A vacuum pump, such as the vacuum pump200illustrated inFIG. 7, is then operated. The vacuum pump is in fluid communication with a port of the cooling chamber14, such as port20. The vacuum pump is configured to evacuate moist air from equipment, such as the chamber or vessel100illustrated inFIG. 7. The equipment from which moist air is evacuated is in fluid communication with the opposite port of the cooling chamber14, such as port18.

Thus, moist air is received through the port18of the cooling chamber14in response to operation of the vacuum pump. The baffle32in the interior of the cooling chamber14serves to urge the moist air down toward the inner bottom surface34of the cooling chamber14and then up before substantially dry air exits the port20of the cooling chamber14. For example, the air may take a path similar to that shown by the arrow inFIG. 2. In this regard, the baffle serves to direct the air along the relatively cold surfaces of the cooling chamber14to enhance moisture removal. The baffle32can also encourage the air to travel proximate the first sidewall of the cooling chamber14through which the first port18extends as the air travels downward from the port18and can also encourage the air to travel proximate the sidewall of the cooling chamber14through which the second port20extends as the air travels upward toward the port20.

Moisture is removed from the air as it travels through the cooling chamber14; the moisture removal is enhanced by directing the air along the relatively cold surfaces of the cooling chamber14. Water vapor in the air condenses and collects at the inner bottom surface34of the cooling chamber. As described above, the lid22may include an optically transparent or translucent material to allow a user to observe moisture as it gathers in the cooling chamber14. After the vacuum process has been completed, the user may open the lid22and remove the moisture from the cooling chamber14, such as by absorption or suction. Additionally or alternatively, an automatic or manual valve and/or a drain may be included at the bottom of the cooling chamber to allow moisture to flow therefrom.

In some embodiments, a temperature sensor is placed in the interior of the cooling chamber14. This can allow a user to monitor the temperature of the cooling chamber14and, for example, determine when the cooling chamber14has reached a steady state temperature. Moreover, the temperature sensor may be in communication with a controller, and the controller may also be in communication with other components (e.g., the fan30, the power adapter62, etc.) to regulate the temperature of the cooling chamber14. The controller may be separate from the moisture trap10or may be integrated with the moisture trap10. For example, the controller may be housed within the box60.

The moisture trap described herein can provide several advantages over traditional moisture removing devices used in these applications. The cold temperatures and directed air flow path can remove moisture more efficiently than traditional devices. In particular, desiccant dryers may be somewhat efficient when the desiccants are initially dry; however, they may quickly lose their efficiency as the desiccants inevitably become wet from moist air flowing therethrough. Accordingly, these dryers must be continually replaced or recycled, adding cost and causing downtime. Moreover, moisture can enter the vacuum pump even when these dryers are replaced or recycled regularly.

Vacuum pumps employ lubricants such as oil to reduce friction between moving parts and to protect seals. Any moisture entering the vacuum pump serves to dilute the lubricant and reduce its effectiveness. As a result, any moisture entering the pump necessitates increased oil changes, which increase cost, produce waste, and create downtime. Moreover, the gradual breakdown of the lubricant during operation decreases the lifetime of the pump due to friction between parts and breakdown of seals.

Furthermore, the moisture trap described herein allows for a relatively unobstructed flow path through the moisture trap. This is in contrast to other dryers such as desiccant dryers, which can create considerably more resistance. The vacuum pump must work harder and requires more power input due to increased flow resistance.

The moisture trap described herein can improve the efficiency of the vacuum pump in another way: the pressure is reduced inside the cooling chamber as moisture is condensed. This creates an increased pressure gradient between the equipment to be evacuated (e.g., chamber or vessel containing moist air) and the vacuum pump, thereby increasing the efficiency of the pump.

The moisture trap can also provide an environmentally-friendly solution. Its enhanced moisture removing capabilities and relatively unobstructed air flow path can reduce the power consumption of the vacuum pump. The reduction of moisture entering the pump also increases the lifetime of the pump, therefore eliminating waste created by disposing of the pump unnecessarily early. Along the same lines, the reduction in moisture entering the vacuum pump reduces the number of required oil changes, which create oil waste that is difficult to dispose and harmful to the environment.

As described above, the configuration of the moisture trap also allows for a lightweight, portable solution. In some embodiments, the footprint of the moisture trap is less than about 100 square inches, and in other embodiments less than about 88 square inches. In some embodiments, the moisture trap weighs less than about 10 pounds, and in other embodiments weighs less than about 8 pounds.

The moisture trap is suitable to be used in laboratory applications, such as the testing of compacted and loose paving mixtures. The lightweight and portable nature of the moisture trap allow for easy manipulation and movement required in these environments. Moreover, the connectors/ports of the moisture trap can allow for easy connection of components such as vacuum pumps and vessels.

The moisture trap is also configured to be operated continuously, thereby improving the accuracy, reliability and repeatability of tests. This is in contrast to other dryers, such as desiccant dryers, that need constant replacement, increasing downtime and potentially compromising repeatability of test conditions.

The moisture trap can be used in systems designed to dry compacted asphalt samples for testing, such as the systems disclosed in U.S. Patent Application Publication No. 2005/0102851 to He et al., the disclosure of which is incorporated herein in its entirety. In particular, the moisture trap10can be positioned between a chamber containing an initially wet compacted asphalt sample and a vacuum pump configured to evacuate moist air from the chamber. In some embodiments, the sample in the chamber is exposed to alternating cycles of applied vacuum and ambient or heated air to keep the sample at a relatively constant temperature. For example, the chamber may include two ports, with vacuum being applied through one port and ambient air supplied through another port. At least during the vacuum cycle, the moisture trap10can prevent moist air evacuated from the chamber from entering the vacuum pump. In these systems, the cycling can continue until the pressure in the chamber is less than 10 TORR, which indicates that the compacted asphalt sample is dry.

The moisture trap10can also be used in the testing of loose asphalt mixtures. For example, the moisture trap can be used in tests for determining maximum specific gravity and density of bituminous paving mixtures. These tests are described in ASTM Test D2041 and AASHTO Test T209, the disclosures of each of which are incorporated herein in their entireties. Vacuum pumps are used in these tests to reduce the pressure in a vessel containing a test sample submerged in water (the vacuum pump is also used to remove air from the sample). The tests require the use of one or more 1000 mL filter flasks, or the equivalent, installed between the vessel and the vacuum pump to reduce the amount of water vapor entering the pump. Current practice is to use one or more desiccant dryers; however, these dryers have several drawbacks as detailed above.

FIG. 8illustrates operations for determining the maximum specific gravity or density of a test sample using a portable moisture trap. A portable moisture trap in a fluid path connecting a vessel adapted to hold a test sample and a vacuum pump is provided (Block300). The portable moisture trap includes a cooling chamber having a first port connected to the vessel and a second port connected to the vacuum pump. The portable moisture trap also includes a thermoelectric device. In some embodiments, the portable moisture trap can include other components described above in reference to the moisture trap10. The cooling chamber is cooled using the thermoelectric device (Block305). The test sample is weighed to determine a dry mass of the sample (Block310). Subsequently, the test sample is placed in the vessel (Block315). Water is added to the vessel to submerge the test sample (Block320).

Moist air is evacuated from the vessel while the test sample is submerged and the pressure in the vessel is reduced using the vacuum pump. This evacuating step can be carried out by the following: flowing moist air from the vessel through the first port of the cooling chamber (Block325); then removing moisture from the moist air in the cooling chamber (Block330); and then flowing substantially dry air through the second port of the cooling chamber toward the vacuum pump (Block335). In some embodiments, the cooling chamber includes a baffle extending downwardly in the cooling chamber from a location proximate a lid to a location proximate an inner bottom surface of the cooling chamber, and the step of removing moisture (Block330) includes urging moist air down toward the inner bottom surface of the cooling chamber. In some embodiments, the baffle comprises a plate that extends across the cooling chamber and contacts opposing corners or sidewalls so that the first port is on one side of the plate and the second port is on the other side of the plate, wherein the plate has a bottom edge with alternating downward projections and valleys that resides proximate the inner bottom surface of the cooling chamber, and the step of removing moisture (Block330) includes flowing moist air through the valleys of the baffle.

Subsequently, the volume of the sample is determined (Block340). In some embodiments, the step of determining the volume of the sample includes: submerging the vessel with the test sample in a water bath; and determining an underwater weight of the test sample. In some other embodiments, the step of determining the volume of the sample includes: filling a known volume vessel with the sample and water; and weighing the filled vessel in air.

Finally, the density and/or specific gravity of the test sample is calculated using the determined dry mass and the determined volume of the sample (Block345). The density is calculated by dividing the dry mass by the volume. The maximum specific gravity is the ratio of the mass of the sample to the mass of an equal volume of water.