Patent Description:
Heat exchangers are often used to transfer heat between two fluids. For example, in aircraft environmental control systems, heat exchangers may be used to transfer heat between a relatively hot air source (e.g., bleed air from a gas turbine engine) and a relatively cool air source (e.g., ram air). Some heat exchangers, often referred to as plate-fin heat exchangers, include a plate-fin core having multiple heat transfer sheets arranged in layers to define air passages there between. Closure bars seal alternating inlets of hot air and cool air inlet sides of the core. Accordingly, hot air and cool air are directed through alternating passages to form alternating layers of hot and cool air within the core. Heat is transferred between the hot and cool air via the heat transfer sheets that separate the layers. In addition, to facilitate heat transfer between the layers, each of the passages can include heat transfer fins, often formed of a material with high thermal conductivity (e.g., aluminum), that are oriented in the direction of the flow within the passage. The heat transfer fins increase turbulence and a surface area that is exposed to the airflow, thereby enhancing heat transfer between the layers.

In some applications, heat exchangers can be exposed to extremely cold temperatures. When a heat exchanger is exposed to extremely cold temperatures ice accretion can occur. When there is ice accretion on a heat exchanger the ice accretion can result in restricting airflow into or out of the heat exchanger.

There is provided a heat exchanger as defined by claim <NUM>.

Also provided is a method for guiding a hot flow and a cold flow through a heat exchanger as defined by claim <NUM>.

The present disclosure relates to a plate-fin heat exchanger. The plate-fin heat exchanger includes a first layer and a second layer. The first layer is configured for cold airflow while the second layer is configured for hot airflow. The second layer is further configured to direct hot air above or below the inlet for the first layer. The hot air above or below the inlet for the first layer helps prevent ice accretion on the inlet side of the first layer. The plate fin heat exchanger will be described below with reference to <FIG>.

<FIG> is a perspective view of heat exchanger <NUM>. Heat exchanger <NUM> includes first end <NUM>, second end <NUM>, first side <NUM>, second side <NUM>, first layer <NUM>, second layer <NUM>, and parting sheet <NUM>. First layer <NUM> includes inlet <NUM> and outlet <NUM>. Second layer <NUM> includes melt flow passage or first passage <NUM>, last pass passage or second passage <NUM>, counterflow passage or third passage <NUM>, inlet <NUM>, and outlet <NUM>. Parting sheet <NUM> separates first layer <NUM> from second layer <NUM> and enables heat transfer therebetween. Inlet <NUM> of first layer <NUM> is at first end <NUM> and extends from first side <NUM> to second side <NUM>. Outlet <NUM> of first layer <NUM> is at second end <NUM> and extends from first side <NUM> to second side <NUM>. First passage <NUM> of second layer <NUM> is at first end <NUM> and extends from first side <NUM> to second side <NUM>. Inlet <NUM> of second layer <NUM> is at first side <NUM> of first passage <NUM>. Second passage <NUM> of second layer <NUM> is adjacent to first passage <NUM> of second layer <NUM> and extends from first side <NUM> to second side <NUM>. Outlet <NUM> of second layer <NUM> is at first side <NUM> of second passage <NUM>. Third passage <NUM> of second layer <NUM> extends from second end <NUM> toward second passage <NUM>. First passage <NUM> is fluidically connected to third passage <NUM> proximate second end <NUM>. Third passage <NUM> is fluidically connected to second passage <NUM> such that third passage <NUM> is fluidically connected in series between first passage <NUM> and second passage <NUM>.

In the aspect of the disclosure shown in <FIG> there are only two layers, first layer <NUM> and second layer <NUM>. In other aspects of the disclosure, heat exchanger <NUM> can include multiple layers alternating between first layer <NUM> and second layer <NUM> with parting sheet <NUM> between each layer. Heat exchanger <NUM> can be made from aluminum, stainless steel, titanium, or any other material suitable for heat exchangers.

<FIG> is a cross-sectional view of heat exchanger <NUM> taken along line A-A in <FIG>, showing first layer <NUM> of heat exchanger <NUM>. First layer <NUM> includes first closure bar <NUM>, second closure bar <NUM>, plurality of fins <NUM>, plurality of passages <NUM> and cold flow FC. First closure bar <NUM> is on first side <NUM> and extends from first end <NUM> to second end <NUM>. Second closure bar <NUM> is on second side <NUM> and extends from first end <NUM> to second end <NUM>. Plurality of fins <NUM> are between first closure bar <NUM> and second closure bar <NUM> and extends from first end <NUM> to second end <NUM>. Plurality of fins <NUM> define plurality of passages <NUM> extending from first end <NUM> to second end <NUM>.

In operation, cold flow FC enters heat exchanger <NUM> at inlet <NUM> of first layer <NUM>. Cold flow FC flows through plurality of passages <NUM> from first end <NUM> to second end <NUM>. Then cold flow FC flows out of heat exchanger <NUM> through outlet <NUM> of first layer <NUM>. As cold flow FC flows through plurality of passages <NUM> in first layer <NUM>, cold flow FC absorbs heat from plurality of fins <NUM> and first closure bar <NUM> and second closure bar <NUM>.

<FIG> is a cross-sectional view of heat exchanger <NUM> taken along line B-B in <FIG>, showing second layer <NUM> of heat exchanger <NUM>. As discussed in reference to <FIG> above, second layer <NUM> includes first passage <NUM>, second passage <NUM>, and third passage <NUM>. Third passage <NUM> includes first portion <NUM>, second portion <NUM>, third portion <NUM>, first turn <NUM>, and second turn <NUM>. Second layer <NUM> also includes first closure bar <NUM>, second closure bar <NUM>, third closure bar <NUM>, fourth closure bar <NUM>, fifth closure bar <NUM>, and sixth closure bar <NUM>. Second layer <NUM> also includes first plurality of fins <NUM>, second plurality of fins <NUM>, third plurality of fins <NUM>, fourth plurality of fins <NUM>, fifth plurality of fins <NUM>, and hot flow FH.

As shown in <FIG>, first passage <NUM> is upstream to first portion <NUM> of third passage <NUM>, and third portion <NUM> of third passage <NUM> is fluidically upstream to second passage <NUM>. First portion <NUM> of third passage <NUM> extends from first side <NUM> to second side <NUM>. Second portion <NUM> of third passage <NUM> extends from first portion <NUM> toward first end <NUM>. Third portion <NUM> of third passage <NUM> is between second passage <NUM> and second portion <NUM> and extends from first side <NUM> to second side <NUM>. First turn <NUM> is between first portion <NUM> and second portion <NUM>. Second turn <NUM> is between second portion <NUM> and third portion <NUM>.

First closure bar <NUM> is on first end <NUM> and extends from first side <NUM> to second side <NUM>. Second closure bar <NUM> is between first passage <NUM> and second passage <NUM> and extends from first side <NUM> to second side <NUM> and separates first passage <NUM> and second passage <NUM>. Third closure bar <NUM> is between second passage <NUM> and third portion <NUM> of third passage <NUM> and extends from first side <NUM> to second side <NUM>. Third closure bar <NUM> separates second passage <NUM> and third portion <NUM> of third passage <NUM>. Fourth closure bar <NUM> is on second end <NUM> and extends from first side <NUM> to second side <NUM>. Fifth closure bar <NUM> is on first side <NUM> and extends from third closure bar <NUM> toward fourth closure bar <NUM>. Sixth closure bar <NUM> is on second side <NUM> and extends from fourth closure bar <NUM> toward third closure bar <NUM>. Fifth closure bar <NUM> and sixth closure bar <NUM> form the sides of second portion <NUM> of third passage <NUM>. In the aspect of the disclosure depicted in <FIG>, second closure bar <NUM> has a thickness equal to two closure bars. The extra thickness of second closure bar <NUM> improves the insulation between first passage <NUM> and second passage <NUM>. The insulation between first passage <NUM> and second passage <NUM> attenuates the heat transfer between hot air flow FH in first passage <NUM> and hot air flow FH in second passage <NUM>. The attenuated heat transfer between hot air flow FH in first passage <NUM> and hot air flow FH in second passage <NUM> helps control the temperature of hot air flow FH throughout second layer <NUM>. Controlling the of hot air flow FH through attenuating heat transfer between hot air flow FH in first passage <NUM> and hot air flow FH in second passage <NUM> the likelihood of damage (e.g., warping or twisting) to second layer <NUM> from exposure to extremely high temperatures.

First plurality of fins <NUM> is in first passage <NUM> and extends in a direction parallel to second closure bar <NUM> and extend from first side <NUM> to second side <NUM>. Second plurality of fins <NUM> is in second passage <NUM> and extends in a direction parallel to second closure bar <NUM> and extends from first side <NUM> to second side <NUM>. Third plurality of fins <NUM> is in first portion <NUM> of third passage <NUM> and extends in a direction parallel to fourth closure bar <NUM>. Fourth plurality of fins <NUM> is in the second portion <NUM> of third passage <NUM> and extends in a direction parallel to fifth closure bar <NUM> and sixth closure bar <NUM>. Fifth plurality of fins <NUM> is in third portion <NUM> of third passage <NUM> and extends in a direction parallel to third closure bar <NUM>.

In operation, hot flow FH enters heat exchanger <NUM> through inlet <NUM> of second layer <NUM> and first plurality of fins <NUM> guides hot flow FH through first passage <NUM>. Hot flow FH travels in first passage <NUM> from first side <NUM> to second side <NUM>. As hot flow FH travels in first passage <NUM>, heat is transferred from hot flow FH into first plurality of fins <NUM> and parting sheet <NUM> to warm inlet <NUM> of first layer <NUM> and prevent ice accumulation at inlet <NUM> of first layer <NUM>. Hot flow FH flows out of first passage <NUM> at second side <NUM> and is routed into first section <NUM> of third passage <NUM> at second end <NUM> of heat exchanger <NUM>. An insulated manifold, tube, or passage, neither of which are shown in <FIG>, can connect first passage <NUM> to third passage <NUM>. In third passage <NUM>, third plurality of fins <NUM> directs hot flow FH through first section <NUM> of third passage <NUM>. Hot flow FH turns at first turn <NUM> and fourth plurality of fins <NUM> directs hot flow FH through second section <NUM> of third passage <NUM>. As hot flow FH travels in second section <NUM>, hot flow FH travels away from second end <NUM> and toward first end <NUM> in a direction that is counter to the flow direction of cold flow FC in first layer <NUM>. Hot flow FH turns toward second side <NUM> at second turn <NUM> and fifth plurality of fins <NUM> directs hot flow FH through third section <NUM> of third passage <NUM> toward second side <NUM>. Hot flow FH is then guided into second passage <NUM>. Hot flow FH can be guided from third section <NUM> of third passage <NUM> into second passage <NUM> by a turning manifold or tube (not shown) connected to second side <NUM>. Second plurality of fins <NUM> directs hot flow FH through second passage <NUM>. Hot flow FH travels in second passage <NUM> from second side <NUM> toward first side <NUM>. Lastly, hot flow FH exits second passage <NUM> at outlet <NUM> on first side <NUM>. Because hot flow FH enters second layer <NUM> at first end <NUM>, then travels from second end <NUM> toward first end <NUM> and exits between first end <NUM> and second end <NUM>, first end <NUM> and second end <NUM> are warmer than outlet <NUM> of second layer <NUM>. Thus, if the temperature at outlet <NUM> of second layer <NUM> is controlled above freezing, the rest of heat exchanger <NUM> will be above freezing and prevent ice formation and accumulation throughout heat exchanger <NUM>.

<FIG> is a cross-sectional view of another embodiment of heat exchanger <NUM> taken, showing second layer <NUM> of heat exchanger <NUM>. Second layer <NUM> of heat exchanger <NUM>, as depicted in <FIG>, includes all elements of heat exchanger <NUM> as shown in <FIG>, and is configured and functions similarly to heat exchanger <NUM> of <FIG> with the addition of seventh closure bar <NUM> and insulation zone <NUM>.

As shown in <FIG>, seventh closure bar <NUM> is between second closure bar <NUM> and second passage <NUM> and extends from first side <NUM> to second side <NUM>. Insulation zone <NUM> is defined by a space between second closure bar <NUM> and seventh closure bar <NUM> extending from first side <NUM> to second side <NUM>. Insulation zone <NUM> provides insulation between first passage <NUM> and second passage <NUM>. Insulation zone <NUM> decreases the heat transfer between hot air flow FH in first passage <NUM> and hot air flow FH in second passage <NUM>. The insulation between first passage <NUM> and second passage <NUM> attenuates the heat transfer between hot air flow FH in first passage <NUM> and hot air flow FH in second passage <NUM>. The attenuated heat transfer between hot air flow FH in first passage <NUM> and hot air flow FH in second passage <NUM> helps control the temperature of hot air flow FH throughout second layer <NUM>. Controlling the of hot air flow FH through attenuating heat transfer between hot air flow FH in first passage <NUM> and hot air flow FH in second passage <NUM> the likelihood of damage (e.g., warping or twisting) to second layer <NUM> from exposure to extremely high temperatures.

In the aspects of the disclosure as shown in <FIG>, <FIG>, and <FIG> second layer <NUM> includes melt pass passage or first passage <NUM>, last pass passage or second passage <NUM>, and counterflow passage or third passage <NUM>. Each of first passage <NUM>, second passage <NUM>, and third passage <NUM> will be described further in the following paragraphs.

As discussed above in paragraphs [<NUM>] and [<NUM>] hot flow FH enters second layer <NUM> of heat exchanger <NUM> at inlet <NUM> of first passage <NUM>. As hot flow FH enters second layer <NUM> of heat exchanger <NUM> at inlet <NUM>, hot flow FH is the hottest air in heat exchanger <NUM>. Therefore, the location of first passage <NUM>, on first end <NUM> extending from first side <NUM> to second side <NUM> helps prevent ice accretion on the structure surrounding inlet <NUM> of first layer <NUM>. Eliminating ice accretion on the structure surrounding inlet <NUM> of first layer <NUM> mitigates undesirable restrictions to both cold flow FC and hot flow FH throughout heat exchanger <NUM>.

The location of last pass passage or second passage <NUM> is important as the location of second passage <NUM> enables first passage <NUM> to be proximate first end <NUM> to aid in preventing ice accretion on the structure surrounding inlet <NUM> of first layer <NUM>. Furthermore, the location of second passage <NUM> enables an increased surface area for third passage <NUM> to encourage heat transfer between first layer <NUM> and second layer <NUM>.

Counterflow passage or third passage <NUM> improves the heat transfer between cold flow in first layer <NUM> and hot flow FH in second layer <NUM> through parting sheet <NUM>. Directing hot flow FH through third passage <NUM>, in a direction opposite to the cold flow FC in first layer <NUM>, improves the heat transfer between cold flow FC in first layer <NUM> and hot flow FH in second layer <NUM>. Furthermore, the configuration of third passage <NUM> decreases the pressure drop through heat exchanger <NUM> as third passage <NUM> is wider than first passage <NUM> and third passage <NUM> and contains fewer turns than traditional heat exchangers.

In one aspect of the disclosure, a heat exchanger includes a first end opposite a second end and a first side opposite a second side. The first side and the second side extend from the first end to the second end. The heat exchanger further includes a first layer and a second layer. The first layer includes an inlet at the first end of the heat exchanger and an outlet at the second end of the heat exchanger. The second layer includes a first passage at the first end of the heat exchanger. The first passage extends from the first side to the second side. The second layer further includes a second passage adjacent to the first passage. The second passage extends from the first side to the second side. The second layer further includes a third passage extending from the second end toward the second passage. The first passage is fluidically connected to the third passage proximate the second end and the third passage is fluidically connected to the second passage.

The heat exchanger of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:.

In another aspect of the disclosure, a heat exchanger includes a first end opposite a second end, a first side opposite a second side, a first layer, and a second layer. The first side and the second side extend from the first end to the second end. The first layer includes an inlet at the first end of the heat exchanger and an outlet at the second end of the heat exchanger. The second layer includes a first passage at the first end of the heat exchanger. The first passage extends from the first side to the second side. The second layer further includes a second passage adjacent to the first passage. The second passage extends from the first side to the second side. The second layer further includes a third passage extending from the second end toward the second passage. The third passage is fluidically connected between the first passage and the second passage.

In another aspect of the disclosure, a method for guiding a hot flow and a cold flow through a heat exchanger. The method includes directing the cold flow through an inlet of a cold layer at a first end of the heat exchanger and out an outlet at a second end of the heat exchanger opposite the first end. The method further includes directing the hot flow through an inlet of a hot layer and into a melt pass passage of the hot layer at the first end. The melt pass passage extends from a first side of the heat exchanger to a second side of the heat exchanger. The first side and the second side both extend from the first end to the second end of the heat exchanger. The method further includes directing the hot flow out of the melt pass passage, to the second end, and into a counterflow passage. The counterflow passage extends from the second end toward the first end between the first side and the second side of the heat exchanger. The method further includes directing the hot flow from the second end toward the first end in the counterflow passage and directing the hot flow out of the counterflow passage and into a last pass passage. The last pass passage is between the melt pass passage and the counterflow passage and extends from the second side to the first side.

The method of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:.

Claim 1:
A heat exchanger comprising:
a first end (<NUM>) opposite a second end (<NUM>);
a first side (<NUM>) opposite a second side (<NUM>), wherein the first side and the second side extend from the first end to the second end;
a first layer (<NUM>) comprising:
an inlet (<NUM>) at the first end of the heat exchanger; and
an outlet (<NUM>) at the second end of the heat exchanger; and
a second layer (<NUM>) comprising:
a first passage (<NUM>) at the first end of the heat exchanger and extending from the first side to the second side, wherein an inlet of the second layer is formed at the first side of the first passage;
a second passage (<NUM>) adjacent to the first passage, wherein the second passage extends from the first side to the second side, the outlet of the second passage being located on the first side; and
a third passage (<NUM>) extending from the second end toward the second passage, the heat exchanger being characterized in that the first passage is fluidically connected to the third passage proximate the second end such that an inlet of the third passage is formed on the first side, and wherein the third passage is fluidically connected to the second passage.