Heat pump and fan coil unit with thermal energy storage and thermal expansion valve in flow conduits extending therebetween

Abstract

An air conditioning system, having: a heat pump having a heat pump coil, a fan coil unit (an FCU) having an FCU coil, a first conduit and a second conduit connecting the heat pump to the FCU coil, wherein the first conduit, the second conduit, the heat pump coil and the FCU coil define a loop; a working fluid in the loop; and a thermal energy storage unit (a TES unit) coupled to the first conduit; a thermal expansion valve (a TXV) including a TXV body coupled to the second conduit, and a bulb coupled to the first conduit, between the TES unit and the heat pump.

Description

CROSS REFERENCE TO A RELATED APPLICATION

[0001] The application claims the benefit of U.S. Provisional Application No. 63 / 735,392 filed Dec. 18, 2024, the contents of which are hereby incorporated in their entirety.BACKGROUND

[0002] The embodiments described herein are directed to air conditioning systems and more specifically to an air conditioning system with a heat pump and a fan coil unit, with thermal energy storage and a thermal expansion valve in flow conduits extending therebetween.

[0003] Traditional heat pump (HP) defrost-cycles take heat from the indoor space, requiring resistance heat for homeowner comfort. Starting in about 2029, a 2% penalty will be applied to HSPF2 (heating season performance factor, a rating by the US Department of Energy) if a defrost cycle uses the indoor blower of the air conditioning system and resistance (electric) heat.BRIEF SUMMARY

[0004] Disclosed is an air conditioning system, including: a heat pump having a heat pump coil, a fan coil unit (an FCU) having an FCU coil, a first conduit and a second conduit connecting the heat pump to the FCU coil, wherein the first conduit, the second conduit, the heat pump coil and the FCU coil define a loop; a working fluid in the loop; and a thermal energy storage unit (a TES unit) coupled to the first conduit; a thermal expansion valve (a TXV) including a TXV body coupled to the second conduit, and a bulb coupled to the first conduit, between the TES unit and the heat pump.

[0005] In addition to one or more aspects of the system or as an alternate, the working fluid is refrigerant.

[0006] In addition to one or more aspects of the system or as an alternate, the TES unit includes a phase change material.

[0007] In addition to one or more aspects of the system or as an alternate, the phase change material is wax.

[0008] In addition to one or more aspects of the system or as an alternate, the phase change material is paraffin wax.

[0009] In addition to one or more aspects of the system or as an alternate, the heat pump is configured to operate in a heating mode, wherein the heat pump is configured to superheat the refrigerant and urge the refrigerant toward the TES unit and the FCU in the first conduit, wherein the phase change material is configured to melt and absorb heat, and de-superheat the refrigerant.

[0010] In addition to one or more aspects of the system or as an alternate, the heat pump is configured to operate in a defrost mode, wherein the heat pump is configured to urge the refrigerant toward the heat pump in the first conduit, and the phase change material is configured to release heat to the refrigerant and solidify, and the refrigerant is configured to defrost the heat pump coil.

[0011] In addition to one or more aspects of the system or as an alternate, when the heat pump is operating in the defrost mode, the bulb is configured to react to an increasing in pressure in the first conduit due to heating and expansion of the refrigerant from the TES unit, to thereby modify a flowthrough configuration of the TXV, and modulating expansion of the refrigerant through the TES unit.

[0012] In addition to one or more aspects of the system or as an alternate, the TXV includes a bypass loop and a bypass valve, and when the heat pump operates in the heating mode, the bypass valve is in an opened state and the refrigerant flows through the bypass loop.

[0013] In addition to one or more aspects of the system or as an alternate, the heat pump is configured for operating in a cooling mode, and when the heat pump operates in the cooling mode, the bulb is configured to react to an increasing in pressure in the first conduit due to heating and expansion of the refrigerant in the loop, around the TES, and thereby modify the flowthrough configuration of the TXV, and modulating expansion of the refrigerant through the loop.

[0014] Disclosed is a method of operating an air conditioning system, the method including: directing a flow in a loop in a first direction or a second direction that is opposite the first direction, wherein the first direction includes the flow flowing though: a heat pump coil in a heat pump; a first conduit extending between the heat pump coil and a fan coil unit coil (an FCU coil) in an FCU; the FCU coil; a second conduit connecting between the heat pump coil and the FCU coil, to the heat pump coil, wherein a thermal energy storage unit (a TES unit) coupled to the first conduit; a thermal expansion valve (a TXV) having a TXV body coupled to the second conduit, and a bulb coupled to the first conduit, between the TES unit and the heat pump.

[0015] In addition to one or more aspects of the method or as an alternate, the flow is a working fluid that is refrigerant.

[0016] In addition to one or more aspects of the method or as an alternate, the TES unit includes a phase change material (a PCM).

[0017] In addition to one or more aspects of the method or as an alternate, the PCM is wax.

[0018] In addition to one or more aspects of the method or as an alternate, the phase change material is paraffin wax.

[0019] In addition to one or more aspects of the method or as an alternate, the method includes operating the heat pump in a heating mode, wherein the heat pump superheats the refrigerant and urges the refrigerant toward the TES unit and the FCU in the first conduit, wherein the PCM melts and absorbs heat, and de-superheats the refrigerant.

[0020] In addition to one or more aspects of the method or as an alternate, the method includes operating the heat pump in a defrost mode, wherein the heat pump urges the refrigerant toward the heat pump in the first conduit, such that the flow, in the loop, flows in the second direction, and the phase change material releases heat to the refrigerant and solidifies, and the refrigerant defrosts the heat pump coil.

[0021] In addition to one or more aspects of the method or as an alternate, the bulb reacts to an increasing in pressure in the first conduit, when the heat pump is operating in the defrost mode, due to heating and expansion of the refrigerant from the TES unit, thereby modifying a flowthrough configuration in the TXV, and modulating expansion of the refrigerant through the TES unit.

[0022] In addition to one or more aspects of the method or as an alternate, the method includes a bypass valve in the TXV opening responsive to the heat pump operating in the heating mode, so that the refrigerant flows through a bypass loop in the TXV.

[0023] In addition to one or more aspects of the method or as an alternate, the method includes operating the heat pump in a cooling mode, to urge the refrigerant toward the heat pump in the first conduit, such that the flow in the loop is in the second direction; and the bulb reacts to an increasing in pressure in the first conduit, when the heat pump operates in the cooling mode, due to heating and expansion of the refrigerant in the loop, around the TES, thereby modifying the flowthrough configuration in the TXV, and modulating expansion of the refrigerant through the loop.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present disclosure is illustrated by way of example and not limited to the accompanying figures in which like reference numerals indicate similar elements.

[0025] FIG. 1A shows an air conditioning system having a heat pump and a fan coil unit with thermal energy storage and a thermal expansion valve in flow conduits extending therebetween, where the system is in a heating mode, according to an embodiment;

[0026] FIG. 1B shows details of a thermal expansion valve (TXV) assembly utilized in the system of FIG. 1A;

[0027] FIG. 2 shows the system of FIG. 1 in a defrost mode;

[0028] FIG. 3 shows the system of FIG. 1 in a cooling mode; and

[0029] FIG. 4 shows a method of operating an air conditioning system, according to an embodiment.DETAILED DESCRIPTION

[0030] FIG. 1A shows an air conditioning (AC) system 100 of a building 110. The phrase “air conditioning” is intended to include one or more of heating, cooling, ventilation, humidification, dehumidification, and other known fluid processing operations, or a combination of any of the above. The AC system 100 includes an outdoor heat pump condensing unit 120 (or heat pump). The heat pump 120 is shown schematically and configured to both cool the building 110 in the summer and heat the building 110 in the winter by reversing a flow of a working fluid 130, e.g., refrigerant, within the unit. That is, the heat pump 120, operationally controlled by a controller 135, can function in a heating mode and a cooling mode. When in the cooling mode, the heat pump 120 functions like a standard air conditioner condenser. When in the heating mode, the heat pump 120 has the ability to absorb heat from the outside air, e.g., during colder months, to provide heating.

[0031] The heat pump 120 may have a heat pump coil 140. The coil of a heat pump 120 in heating is an evaporator, and contains low pressure refrigerant. The high pressure refrigerant in heating is pumped to the fan coil 220 in the fan coil unit 200 (discussed below) which acts as a condenser. The heat pump 120 has a reversing valve 150, which allows the system to switch between the cooling and heating modes. The heat pump 120 also has a compressor 160 that provides energy for the refrigerant 130 to flow through the system 100.

[0032] In the heat pump 120, rather than a dedicated pump to direct refrigerant 130 to the heat pump coil 140 during defrost, the reversing valve 150 changes the direction of the refrigerant 130, sending hot refrigerant 130 to the heat pump coil 140 to melt frost during the defrost cycle. When the defrost cycle is triggered, the reversing valve 150 flips the direction of flow of the refrigerant 130, allowing hot refrigerant to travel through the heat pump coil 140, which then thaws ice buildup. The defrost sensor 170 on the heat pump coil 140 detects frost accumulation and signals the controller 135 to initiate the defrost cycle.

[0033] The heat pump 120 provides an energy-efficient way to heat and cool a home compared to separate AC and heating systems. However, during operation, the heating mode, when the temperature of the refrigerant 130 in the heat pump coil 140 is relatively low, frost develops on the heat pump coil 140, decreasing its efficiency. Frost may be detected with a defrost sensor 170 coupled to the heat pump coil 140, which that is operatively coupled to the controller 135, which may cause the heat pump 120 to switch to a defrost mode, which heats the heat pump coil 140.

[0034] The system 100 includes an indoor fan coil unit (FCU) 200. The FCU 200 is used to heat or cool a room 210 in the building 110. The FCU 200 includes an FCU coil 220, a fan (or blower) 230 that cooperates with the heat pump 120. The first and second conduits 300, 310 connect the heat pump coil 140 and the FCU coil 220. During a heating cycle, the first conduit 300 may be utilized for transporting a vapor form of the refrigerant 130 while the second conduit 310 may be utilized for transporting a liquid form of the refrigerant 130. The first and second conduits 300, 310, the heat pump coil 140 and the FCU coil 220 form a loop 320.

[0035] The fan 230 forces room air 240 around the FCU coil 220, which is filled with the refrigerant 130, either cooling or heating the room air 240 depending on the mode of operation of the heat pump 120 and the desired temperature in the room 210 as set by a thermostat 250 operationally coupled to the controller 135. The cooled or heated room air 240 is circulated in the room to maintain a comfortable environment. In the FCU 200, the FCU coil 220 is an evaporator coil, for absorbing heat from the room air 240 passing through the FCU 200 to cool the room 210. An FCU 200 functions as an air handler, as it contains the fan 230 to circulate room air 240 and an FCU coil 220 to cool the room air 240.

[0036] As indicated, when the heat pump 120 is in the heating mode, the FCU coil 220 functions as a condenser coil, as it absorbs heat from the refrigerant 130 that has been warmed by the heat pump 120 and transfers that heat to the indoor room air 240 flowing over the FCU coil 220, warming the room air 240 in the room 210. That is, the FCU coil 220 has the opposite effect in the cooling mode as compared with the heating mode, where it functions as an evaporator coil.

[0037] As shown in FIG. 1A, according to an embodiment, the system 100 includes a thermal energy storage (TES) unit 325 coupled to the first conduit 300, near the FCU 200, e.g., on the inside of the building 110. The TES unit 325 includes a phase change material (PCM) 325 which may be wax and more specifically paraffin wax.

[0038] The system 100 includes a thermal expansion valve (a TXV) 265, a passive mechanical device having a TXV body 260 coupled to the second conduit 310, near the FCU 220, and a TXV bulb 270, coupled to the first conduit 300, between the TES 325 and the heat pump 120. Details of the TXV 265 are shown in FIG. 1B.

[0039] The TXV 265 controls the flow of the refrigerant 130 through the loop 320 by reducing pressure in the flow of refrigerant 130. This allows the refrigerant 130 to expand and absorb heat from the air 240, creating a cooling effect. That is, the TXV 265 transforms high-pressure liquid refrigerant 130 into a low-pressure two-phase vapor and liquid that is capable of absorbing heat. Without the TXV 265, the refrigerant 130 might remain at high pressure, preventing efficient cooling and potentially damaging the system.

[0040] The TXV 260 may include a poppet type valve with an inlet port 260A, an outlet port 260B, a poppet 260C, an adjustment spring 260D to control a response of the poppet 260C and a flexible diaphragm 260E. The flexible diaphragm fluidly seals the refrigerant 130 flowing through the TXV 260 and a working fluid 260F in the bulb 270. The working fluid 260F in the bulb 270 may be refrigerant. The TXV 260 may include a bypass valve 280, in a bypass loop 285, which is also a passive component. Refrigerant 130 may bypass the poppet 260C, e.g., to equalize the high and low sides of the system during the off cycle.

[0041] The bulb 270 reacts to temperature changes in the loop 320, around the TES 325. The diaphragm 260E in the TXV body 260 actuates the poppet 260C, and an increasing pressure, e.g., due to expansion of refrigerant in the bulb 270, presses down on the poppet 260C to further open the TXV body 260. The adjustment spring 260C of the TXV body 260 provides a closing force on the TXV body 260 which controls the superheating. An equalization port 260G is utilized when the pressure at the bulb 270 differs from the pressure at the TXV outlet port 260B.

[0042] With the disclosed configuration of the system 100, the heat pump 120 is configured to operate in a different modes, including a heating mode, a cooling mode and a defrost mode. The heating mode is triggered by the controller 135 communicating with the thermostat 250 and the compressor 160 (for heating and urging of the flow). In the heating mode, the refrigerant flow is directed out of the heat pump 120, along the first conduit 300 to the FCU 220, through the FCU coil 220, the second conduit 310 and back to the heat pump 120 to flow through the heat pump coil 140. This flow direction through the loop 320 is referred to as the first flow direction D1.

[0043] In the heating mode, the heat pump 120 superheats the refrigerant 130 and urges the refrigerant 130 in the first conduit 300 toward the TES unit 325 and the FCU 200. The PCM 326 melts and absorbs heat, and de-superheats the refrigerant 130 before it reaches the FCU 200. During this mode of operation, the bypass valve 280 in the TXV 265 is in an opened state and the refrigerant 130 flows through the bypass loop 285.

[0044] Turning to FIG. 2, the defrost mode is triggered by the communications between the defrost sensor 170 coupled to the heat pump coil 140, the controller 135, the reversing valve 150 and the compressor 160 (to urge the flow). In the defrost mode, the refrigerant flow 130 is directed out of the heat pump 120, along the second conduit 310 to the FCU 220, through the FCU coil 220, the first conduit 300 and back to the heat pump 120 to flow through the heat pump coil 140. This flow direction through the loop 320 is referred to as the second flow direction D2, which is opposite the first flow direction D1.

[0045] In the defrost mode, the heat pump 120 is configured to urge the refrigerant 130 toward the heat pump 120 in the first conduit 300. The PCM 326 in the TES unit 325 is configured to release heat to the refrigerant 130, causing the PCM 326 to solidify. The heated refrigerant 130 is configured to defrost the heat pump coil 140.

[0046] When the heat pump 120 is operating in the defrost mode, the bulb 270 is configured to react to an increase in pressure in the first conduit 300 due to heating and expansion of the refrigerant 130 from the TES unit 325. As indicated above and shown in FIG. 1B, the reaction from the bulb 270, e.g., expansion of refrigerant 270F in the bulb 270, further opens the TXV 265, modulating expansion of the refrigerant 130 through the TES unit 325.

[0047] Turning to FIG. 3 the cooling mode is triggered by the controller 135 communicating with the thermostat 250, the reversing valve 150 and the compressor 160 (to urge the flow). In the cooling mode, the refrigerant flow is directed out of the heat pump 120, along the second conduit 310, through the TXV body 260 to expand and cool, then to the FCU 220, through the FCU coil 220, the first conduit 300 and back to the heat pump 120 to flow through the heat pump coil 140, i.e., in the second flow direction D2 in the loop 320.

[0048] In the cooling mode, the bulb 270 of the TXV 265, is configured to react to an increasing in pressure in the first conduit 300 due to heating and expansion of the refrigerant 130 in the loop 310, around the TES 325. From the reaction in the bulb 270, a flow of refrigerant 130 through configuration in the TXV 265 is increased. This modulates expansion of the refrigerant through the loop 320.

[0049] Turning to FIG. 4, a flowchart shows a method of operating the air conditioning system 100. As shown in block 510 the method includes directing a flow 130 in a loop 320 in a first direction D1 or a second direction D2 that is opposite the first direction D1. When the flow 130 is directed in the first direction D1, the flow 130 flows though the heat pump coil 140 in the heat pump 120. The flow 130 then flows through first conduit 300 extending from the heat pump coil 140 to the FCU coil 220 in the FCU 200, and then through the FCU coil 220. The flow 130 then flows through the second conduit 310 extending between the heat pump 120 and the FCU 200, to the heat pump coil 140. The TES unit 325 is coupled to the first conduit 300. The TXV body 260 is coupled to the second conduit 310. The bulb 270 is coupled to the first conduit 300, between the TES unit 325 and the heat pump 120. The TES unit 325 includes the PCM 326 that is wax and more specifically paraffin wax.

[0050] As shown in block 520 the method includes operating the heat pump 120 in a heating mode. In this mode, the heat pump 120 superheats the refrigerant 130 and urges the refrigerant 139 in the first direction D1, toward the TES unit 325 and the FCU 200 in the first conduit 300. The PCM 326 melts and absorbs heat, and de-superheats the refrigerant 130.

[0051] As shown in block 525 the method includes opening a bypass valve 280 in the TXV 265, responsive to the heat pump 120 operating in the heating mode, so that the refrigerant 130 flows through the bypass loop 260D.

[0052] As shown in block 530 the method includes operating the heat pump 120 in a defrost mode. In this mode, the heat pump 120 urges the refrigerant 130 toward the heat pump 120 in the first conduit 300, such that the flow 130 in the loop 320 is in the second direction D2. The PCM 326 releases heat to the refrigerant and solidifies. The refrigerant 130 defrosts the heat pump coil 140.

[0053] The bulb 270 reacts to an increasing in pressure in the first conduit 300, when the heat pump 120 is operating in the defrost mode, due to heating and expansion of the refrigerant 130 from the TES unit 325. From this reaction, a flowthrough configuration in the TXV 265 is modified. This modulates an expansion of the refrigerant 130 through the TES unit 325.

[0054] As shown in block 540, the method includes operating the heat pump 120 in the cooling mode to urge the refrigerant 130 toward the heat pump 120 in the first conduit 300. The bulb 270 reacts to an increasing in pressure in the first conduit 300, when the heat pump 120 operates in the cooling mode, due to heating and expansion of the refrigerant 130 in the loop 320, around the TES 325. From this reaction, a flowthrough configuration in the TXV 265 is modified. This modulates an expansion of the refrigerant 130 through the loop 320.

[0055] The above embodiments provide a TES unit 325 installed on a vapor line 300 of an air conditioning system 100, in series with the FCU 200. The TES unit 325 is charged by de-superheating refrigerant 130 during heating operation. The bulb 270 modulates expansion of the refrigerant 130 during cooling and defrost modes, and is located between the heat pump 120 and the TES unit 325. With this configuration, expansion of the refrigerant 130 is modulated for evaporation in the TES unit 325 during the defrost mode and during evaporation in the FCU coil 220 when operating the heat pump 120 in the cooling mode, when the PCM 326 in the TES unit 325 is solidified and is not releasing heat into the refrigerant 130.

[0056] The embodiments enable defrost of the heat pump coil 140 with stored heat from the TES unit 235 to minimized or remove a need for the use of indoor heat, indoor blower or resistance (electric) heat during a defrost mode of the heat pump 12. Installation of the TES unit 325 in series with the indoor FCU coil 220 allows for a relatively quick installation by avoiding a need for an additional bypass valve.

[0057] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. The term “about” is intended to include the degree of error associated with measurement of the particular quantity and / or manufacturing tolerances based upon the equipment available at the time of filing the application. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and / or groups thereof.

Claims

1. An air conditioning system, comprising:a heat pump having a heat pump coil,a fan coil unit (an FCU) having an FCU coil,a first conduit and a second conduit connecting the heat pump to the FCU coil,wherein the first conduit, the second conduit, the heat pump coil and the FCU coil define a loop;a working fluid in the loop; anda thermal energy storage unit (a TES unit) coupled to the first conduit;a thermal expansion valve (a TXV) including a TXV body coupled to the second conduit, and a bulb coupled to the first conduit, between the TES unit and the heat pump.

2. The system of claim 1, wherein the working fluid is refrigerant.

3. The system of claim 1, wherein the TES unit includes a phase change material.

4. The system of claim 1, wherein the phase change material is wax.

5. The system of claim 1, wherein the phase change material is paraffin wax.

6. The system of claim 1, wherein:the heat pump is configured to operate in a heating mode, wherein the heat pump is configured to superheat the refrigerant and urge the refrigerant toward the TES unit and the FCU in the first conduit, wherein the phase change material is configured to melt and absorb heat, and de-superheat the refrigerant.

7. The system of claim 1, wherein:the heat pump is configured to operate in a defrost mode, wherein the heat pump is configured to urge the refrigerant toward the heat pump in the first conduit, and the phase change material is configured to release heat to the refrigerant and solidify, and the refrigerant is configured to defrost the heat pump coil.

8. The system of claim 1, wherein when the heat pump is operating in the defrost mode, the bulb is configured to react to an increasing in pressure in the first conduit due to heating and expansion of the refrigerant from the TES unit, to thereby modify a flowthrough configuration of the TXV, and modulating expansion of the refrigerant through the TES unit.

9. The system of claim 1, wherein the TXV includes a bypass loop and a bypass valve, and when the heat pump operates in the heating mode, the bypass valve is in an opened state and the refrigerant flows through the bypass loop.

10. The system of claim 1, wherein the heat pump is configured for operating in a cooling mode, and when the heat pump operates in the cooling mode, the bulb is configured to react to an increasing in pressure in the first conduit due to heating and expansion of the refrigerant in the loop, around the TES, and thereby modify the flowthrough configuration of the TXV, and modulating expansion of the refrigerant through the loop.

11. A method of operating an air conditioning system, the method comprising:directing a flow in a loop in a first direction or a second direction that is opposite the first direction, wherein the first direction includes the flow flowing though:a heat pump coil in a heat pump;a first conduit extending between the heat pump coil and a fan coil unit coil (an FCU coil) in an FCU;the FCU coil;a second conduit connecting between the heat pump coil and the FCU coil, to the heat pump coil,wherein a thermal energy storage unit (a TES unit) coupled to the first conduit;a thermal expansion valve (a TXV) having a TXV body coupled to the second conduit, and a bulb coupled to the first conduit, between the TES unit and the heat pump.

12. The method of claim 11, wherein the flow is a working fluid that is refrigerant.

13. The method of claim 11, wherein the TES unit includes a phase change material (a PCM).

14. The method of claim 11, wherein the PCM is wax.

15. The method of claim 11, wherein the phase change material is paraffin wax.

16. The method of claim 11, comprising:operating the heat pump in a heating mode, wherein the heat pump superheats the refrigerant and urges the refrigerant toward the TES unit and the FCU in the first conduit, wherein the PCM melts and absorbs heat, and de-superheats the refrigerant.

17. The method of claim 11, comprising:operating the heat pump in a defrost mode, wherein the heat pump urges the refrigerant toward the heat pump in the first conduit, such that the flow, in the loop, flows in the second direction, and the phase change material releases heat to the refrigerant and solidifies, and the refrigerant defrosts the heat pump coil.

18. The method of claim 11, wherein:the bulb reacts to an increasing in pressure in the first conduit, when the heat pump is operating in the defrost mode, due to heating and expansion of the refrigerant from the TES unit, thereby modifying a flowthrough configuration in the TXV, and modulating expansion of the refrigerant through the TES unit.

19. The method of claim 11, comprising:a bypass valve in the TXV that opens responsive to the heat pump operating in the heating mode, so that the refrigerant flows through a bypass loop in the TXV.

20. The method of claim 11, comprising:operating the heat pump in a cooling mode, to urge the refrigerant toward the heat pump in the first conduit, such that the flow in the loop is in the second direction; andthe bulb reacts to an increasing in pressure in the first conduit, when the heat pump operates in the cooling mode, due to heating and expansion of the refrigerant in the loop, around the TES, thereby modifying the flowthrough configuration in the TXV, and modulating expansion of the refrigerant through the loop.

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