Single port coil capacity modulator
Kind Code:

A coil modulator apparatus for use in connection with heat transfer coil assemblies found in commercial heating and air conditioning units is used to limit the number of active tube sections carrying fluid in cooling coil assemblies. The single port modulator apparatus comprises an inner valve with an inner and outer housing. The modulator has valve ports in the sides of the modulator. The inner valve rotates within the outer housing and the openings in the inner housing correspond to those ports in the outer valve. These openings connect with upstream or downstream tube sections in the bank of tubes and allow flow of fluid to be diverted. The actuator arm of the coil assembly rotates the inner valve thus changing the orientation of the outer and inner valve ports and so diverting fluid flow from various numbers of tubes depending upon how far the actuator is moved.

Koenig, Robert Peter (Westminister, CO, US)
Application Number:
Publication Date:
Filing Date:
Primary Class:
Other Classes:
165/103, 165/101
International Classes:
F28F27/02; (IPC1-7): F24F3/00; F28F27/02
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Primary Examiner:
Attorney, Agent or Firm:
Robert Peter Koeing (1720 W-115 Circle, Westminister, CO, 80234, US)

I claim:

1. A single port modulator for use in connection with heating and air conditions systems that comprise a bank comprising a plurality of tubes having fluid flow through each of said tubes, each of said tubes having at least one upstream section and one downstream section, said down stream section in connection with said supply manifold and an opposite end of said bank, and said upstream sections in connection with said opposite end and said supply manifold; each of said tubes having at least one upstream section where fluid flows away from said inlet end, and at least one downstream section where fluid flows in the direction towards said inlet end, said modulator comprising an inner valve body and an outer valve body, each of said inner and outer valve bodies having a plurality of ports, said ports arranged in pairs, each of said pairs comprising one of said inner valve ports and one of said outer valve ports, said inner valve having an actuator arm in connection with said inner valve and having a means in connection with said inner valve for the rotation of said inner valve and said inlet and outlet passage in relation to said inlet and outlet passage on said outer manifold so as to vary the amount of fluid flow through the downstream sections of said tubes.



[0001] The invention relates to the field of heating and cooling units and an improved modulator for use in re-directing the flow of liquid in the coil bank assembly. It is thought that the primary use of tho invention would be in connection with cooling units since the primary purpose of the invention is to vary the number of active tubes, both upstream and downstream in a bank of tubes.

[0002] A coil assembly is really a bank of tubes, with each tube known as a “tube row” or may be referred to as simply a “tube” in this application. There are both upstream and downstream section to each tube in the coil. Upstream sections are those sections of the tube that carry the flow of water (or other fluid) from that end of the coil from where the supply manifold is and then to the opposite end of the bank. Downstream sections are those sections that carry the flow back i.e. from the opposite end of the bank back to the return manifold at the other end of the bank.

[0003] There are several ways in which these types of coils are used in the industry. For heating only; utilizing hot water, for cooling only; utilizing chilled water and for heating and cooling in what is called a change over system where the heating and cooling medium is changed depending on the needs. The modulator described herein is primarily intended to be used for the cooling application which means air conditioning units, primarily.

[0004] The inner and an outer valve together form the modulator section parts 15/16 in FIG. 4 (cross section shown in FIG. 3) of the present invention that is connected at one end of the tube bank or coil, see FIG. 4. Various tube sections of the coil are then in connection with ports on the outer valve. Ports on the inner valve correspond to those on the outer valve so water will flow into and out of the modulator.

[0005] The rotation of the inner valve varies with respect to the outer valve and this will limit the number of active upstream tube sections in a bank of cooling tubes and that in turn will allow the full travel length of the remaining tube sections to be used by the water flowing through the unit.


[0006] There is not believed to be any prior art systems that use a modulator valve for varying individual tube flow control. Flow control is achieved by rotation of an inner valve and an outer body that form the modulator and the alignment of apertures in each will control the flow of water through various tubes in the bank thus providing a novel system that will vary the travel path of the water in the coil in order to provide maximum heat transfer and a longer circuit path even when there may be less volume of water working in the coil.

[0007] The system is believed to find its greatest use in commercial and institutional types of applications where large air conditioning units are used to cool buildings. The design of most such heating/ac units results in a bank of heat transfer tubes that is fed by an inlet manifold. The flow of water through the tubes connected to the manifold remains unblocked at all times and hence the number of passages through the bank of tubes unrestricted. This means that when less than design volume is required, the overall flow of liquid at the inlet manifold is reduced which results in tubes in the bank receiving uneven and disproportionate flow rates. This results in cycling temperatures (inefficient operation), laminar flow stratification and inefficient system operations.

[0008] It is found that during the majority of operating hours the actual amount of liquid flowing through the coil is less than 30% of the calculated design reqiuremnent. Such units typically operate with this increment of water flowing through the tubes of the unit much of the day. In fact perhaps all day, or many days. The resulting condition means that only a traction of the tubes in the coil are required to satisfy the existing heat transfer requirement. The invention is unique in the while it has the ability to change the number of active tubes, it facilitates maintaining a desirable flow rate through those tubes that remain active.

[0009] The overall capacity at part load, inherent in the prior art systems, causes cyclic control resulting in hot and cold temperature swings throughout the day which prompts complaints from the occupants. This of course means, more building maintenance calls, perhaps more fine tuning of the thermostats in the building and/or other fixes designed for short term alleviation of the problem. Eliminating radical flow and temperature swings also minimizes wear and tear on primary heating and cooling equipment.

[0010] A major concern of all building owners and operators is the operating efficiency of the system. It is the object of the invention to improve overall performance and efficiency by adjusting and matching coil capacity to the load while maintaining the lowest possible system flow rate minimizing the pump energy consumption.

[0011] The invention performs this function by means of a sleeve type inner valve that cuts off or blocks flow to a portion of the tube in response to a control device detecting that full volume flow is not required. Thus the invention restricts flow through certain tube in the bank when such flow is not needed and thereby prevents cycling of temperature that normally occurs when coils operate with more heat transfer surface than is necessary to satisfy the load.


[0012] A coil modulator apparatus for use in connection heat transfer coil assemblies found in commercial and institutional air conditioning units. The coil modulator apparatus comprising an inner valve having valve ports in the sides of the valve that rotates within an outer housing. Apertures in the outer housing are in fluid connection with each tube in the bank of tubes to that the volume of liquid flowing is modulated by the tubes individually.

[0013] A portion of the tube/tubes can be rendered inactive and thus reducing the heat transfer capacity of the coil assembly allowing the active tubes to maintain a relatively high flow rate to eliminate laminar flow and produce a relatively low temperature differential when applied to coils for heating. Thus freeze protection where air temperature is below 32° can enter the coil. The heat transfer capacity is varied by modulating flow through the tube individually as a result of the size, shape and location of inner valve ports.

[0014] It is an object of the invention to provide an improved heat transfer unit that maintains a relatively high flow rate on the liquid side without producing an undesirable condition on the air side.

[0015] Another object of the invention is to prevent the cycling of the building temperatures that results when design heat transfer capacity of the coil assembly exceeds the amount of heating or cooling necessary to meet demand (i.e. over capacity at part load). This condition is common in coil applications where the volume of liquid to the supply manifold is decreased to effect a reduced heat transfer and the effective transfer surface remains constant.

[0016] Another object of the invention is to minimize the need for auxiliary pumps to ensure uniform distribution of liquid during periods of low demand and when two or more coils are used in parallel. By varying all tube openings individually, the coil modulator provides selective circuiting to improve conditions and minimize problems associated with laminar flow.

[0017] Other objects of the invention will become apparent to those skilled in the art once the invention has been shown and described.


[0018] FIG. 1 Inner valve construction;

[0019] FIG. 2 Outer valve body of modulator;

[0020] FIG. 3 cross section of modulator assembly;

[0021] FIG. 4 Standard finned tube coil used to heat or cool air for air conditioning systems;

[0022] FIG. 5 optional connection type for modulator/coil connection.


[0023] The invention is a single port modulator for use in connection with tube rows found in cooling units. See FIGS. 1-3. Typically these cooling units would be air conditioning units found in commercial installations like office buildings. The modulator is essentially a valve that regulates the flow of liquid, such as water going through the bank of tubes. The single port modulator allows the number of active tubes in the bank of tubes to be varied according to system requirements. The modulator could be used in connection with a sensor that detects when the flow demands on the system have diminished and so that it can in turn, diminish the flow through the bank by rotating the inner valve of the modulator.

[0024] The inner valve 1 with ports 7, 9 and 14 fits inside the outer body 2 and these ports 7 and 9 are designed to correspond with the ports 6 and 8 on the outer body.

[0025] The sizes and shapes of all these ports may vary depending on the particular application that the modulator is to be fitted into and the particular requirements of that system. Ports 7 and 9 in the inner valve and ports 6 and 8 in the outer body may be the same shape and size. Detail of port 17 shown in FIG. 6.

[0026] Port 9 may be elongated as shown to allow connection between the ports 9 and 8 to remain open (i.e. to still allow flow of liquid) after ports 6 and 7 have been closed through rotation of the actuator arm 4. I.e. the rotation of the actuator 4 will not close all the ports at the same time but rather the connection between ports 6/7 (outer and inner apertures respectively) will be cut off (i.e. blocked to the passage of fluid) before the connection between 8/9 is closed.

[0027] Hence some ports will remain open for a longer period during the movement of the actuator arm. In this manner, a varying number of ports can be closed/open by movement of the actuator. Since the passages in the coil assembly are each associated with a port on the inner and outer valve then the liquid flow through the passages in the coil can be varied according to the needs of the system.

[0028] See FIG. 3. Ports 17 and 14 are designed, shaped and positioned to allow full flow as required by ports 6, 7, 8 and 9. When ports 7 and 6 are aligned, as shown, full flow is allowed through all the ports.

[0029] Item 13 shows the supply inlet or the return outlet depending on where in the system it is placed during the following procedure:

[0030] The modulator assembly shown FIGS. 1-3 can be applied as a replacement for either the conventional supply header 15 or return header 16 (both the supply header and the return header are shown in FIG. 4) the flow direction will reverse depending on location of the modulator 18 is the manifold that functions to collect the water flowing in from 13 (when the modulator is in the supply location) or to collect the water flowing out from port 17 when the modulator is placed in the return position. The modulator must be substituted for either the conventional supply header 15 or the conventional return header 16.

[0031] When the modulator is placed in the supply location (15 in FIG. 4) flow of liquid will enter the manifold 18 from supply pipe 13 and then flow out of the manifold and into the modulator through ports 17 and 14 and the flow will exit the modulator through ports 6, 7, 8 and 9 then flow into the coil and then exit the coil through return manifold 16.

[0032] When the modulator is placed at the return Position (16 in FIG. 4), flow of liquid will leave the coil and enter the modulator through ports 6, 7, 8 and 9 it will then exit the modulator through ports 17 and 14 and then enter the manifold 18 (shown in FIGS. 2 and 3) and then exit the manifold through return pipe 13 which returns the liquid back to the system. Note: that passage 13 functions as a supply pipe when the modulator substitutes for supply header 15 and passage 13 will function as a return passage when the modulator substitutes for return header 16.

[0033] Methods of connecting the modulator in FIG. 3 to the coil in FIG. 4 are shown in FIG. 5. The coil tube extension 5, and the nipple 12 of the modulator may be joined in any number of ways. Item 6 is a bolted flange and 10 indicates a sweat joint and item 11 represents either flare union or compression fitting. Since return connection 13 requires the largest of all connectors, a union connection would be best suited for that location. In all cases, a screwed type connector is preferred to accommodate removal for servicing.

[0034] The actuator can be controlled on a modulating or pulsed basis with periodic movements of the arm designed to vary the volume flow of liquid in the bank in response to changing temperature conditions. A temperature controller may be used in connection with the arm. The controller would sense changes in the temperature and then send a signal to the inner valve actuator to vary the volume of liquid flow in response.

[0035] The single port modulator that is the subject of the invention then, is likely to be used as an integral part of new coils or as a retrofitted apparatus that can be added to standard pre existing coil assemblies.

[0036] The inlet and outlet manifolds may be referred to as supply and return tubes. One inlet supply manifold feeds all the tubes in the bank. The outlet return manifold collects water from all the tubes in the bank.

[0037] The modulator will thus reduce flow rate through the bank by cutting off some tubes and at the same time will increase the heat transfer surface of the bank in proportion to this reduction. This effect will be to create proportionately greater heat transfer surface which tends to increase the temperature differential between supply and return lines in chilled water systems (i.e. the difference between the water the coil at the supply manifold 1 and the temperature leaving the coil at the return manifold 2 as seen in FIG. 4). Thus resulting in increased chiller efficiency.

[0038] Note: There is one supply manifold 15 and one return manifold 16 that Supplies the entire bank of tubes. See FIG. 4.

[0039] Note. The valve body may be split and held together by a bolt flange or may be of a tubular construction with a removable end cap for maintenance and servicing of the invention.