Method and apparatus for latent heat extraction

• US 5,181,552 A
• Filed: 11/12/1991
• Issued: 01/26/1993
• Est. Priority Date: 11/12/1991
• Status: Expired due to Term

• Current Assignee: Kenneth L. Eiermann
• Original Assignee: Kenneth L. Eiermann
• Inventors: Eiermann, Kenneth L.
• Primary Examiner(s): Wayner, William E.
• Application Number:
  US07/791,120
• Time in Patent Office: 441 Days
• Field of Search: 165/21, 62/90, 62/173, 62/176.5
• US Class Current: 165/228
• CPC Class Codes: F24F 11/00 Control or safety arrangements
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/47 Responding to energy costs
• CPC Class Codes: F24F 11/84 using valves
• CPC Class Codes: F24F 11/85 using variable-flow pumps
• CPC Class Codes: F24F 12/00 Use of energy recovery systems in air conditioning, ventilation or screening with both heat and humidity transfer between supplied and exhausted air F24F3/147
• CPC Class Codes: F24F 2005/0025 using heat exchange fluid storage tanks
• CPC Class Codes: F24F 2011/0002 for admittance of outside air
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 2110/20 Humidity
• CPC Class Codes: F24F 2140/00 Control inputs relating to system states
• CPC Class Codes: F24F 2203/021 Compression cycle
• CPC Class Codes: F24F 2221/183 combined with a hot-water boiler
• CPC Class Codes: F24F 2221/56 Cooling being a secondary aspect
• CPC Class Codes: F24F 3/00 Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems room units F24F1/00
• CPC Class Codes: F24F 3/153 with subsequent heating, i.e. with the air, given the required humidity in the central station, passing a heating element to achieve the required temperature
• CPC Class Codes: F25B 29/003 of the compression type system

Abstract

A method and apparatus for improved latent heat extraction combines a run-around coil system with a condenser heat recovery system to enhance the moisture removing capability of a conventional vapor compression air conditioning unit. The run-around coil system exchanges energy between the return and supply air flows of the air conditioning unit. Energy recovered in the condenser heat recovery system is selectively combined with the run-around system energy extracted from the return air flow to reheat the supply air stream for downstream humidity control. A control system regulates the relative proportions of the extracted return air flow energy and recovered heat energy delivered to the reheat coil for efficient control over moisture in the supply air flow. Auxiliary energy in the form of electric heat energy is further added to the recovered heat energy for additional reheat use.

Claims

1. A moisture control apparatus for use with a fluid compression air conditioning system having a compressor for compressing a compressible fluid, and a cooling coil where the compressible fluid decompresses absorbing thermal energy from a return air flow as a cooled supply air flow, the moisture control apparatus comprising:

a working fluid;

precooling coil means in said return air flow for exchanging thermal energy between the return air flow and the working fluid;

reheat coil means in said supply air flow for exchanging thermal energy between the working fluid and the supply air flow;

heat exchange means for exchanging thermal energy between the compressible fluid and the working fluid;

fluid pump means comprising a variable speed drive fluid pump for motivating a flow of the working fluid through said precooling coil means, said reheat coil means, and said heat exchange means;

fluid conduit means containing the working fluid therein for containedly directing the working fluid through a series arrangement of said precooling coil means, said heat exchange means, and said reheat coil means;

bypass conduit means, connected to said control valve in parallel with said heat exchange means and in parallel with a series combination of said precooling coil means and said reheat coil means, for selectively circulating a first portion of the working fluid as a bypass flow through said series combination of said precooling coil means and said reheat coil means;

regulating means comprising a control valve connected to said fluid conduit means in said series arrangement, said control valve comprising a first input port connected to said fluid conduit means for receiving a first flow of said working fluid from said heat exchange means, a second input port connected to said bypass conduit means for receiving said bypass flow of said working fluid from said precooling coil means, an output port connected to said fluid conduit means for selectively exhausting said first and bypass flows from said control valve to said reheat coil means, and valving means for selectively metering said first and bypass flows through said control valve as a metered flow for regulating said working fluid flow through said precooling and reheat coil; and

,

control means operatively associated with said control valve and said variable speed drive fluid pump for sensing moisture in said supply air flow and for maintaining said sensed moisture at a predetermined set point by regulating i) said valving means to selectively meter said first and bypass flows, and ii) said variable speed drive fluid pump to motivate the metered flow through said series precooling coil means.

2. A moisture control apparatus according to claim 1 further comprising thermal energy storage unit means, connected to said fluid conduit means and operatively associated with said working fluid and said heat exchange means, for recovering and storing thermal energy from said compressible fluid and selectively delivering the stored thermal energy to said working fluid.

3. A humidity control apparatus for use with a cooling coil means for selectively absorbing thermal energy from a return airstream as a cooled airstream, the apparatus comprising:

precooling coil means disposed upstream of said cooling coil means for selectively precooling said return airstream;

reheat coil means disposed downstream of said cooling coil means for selectively reheating the cooled airstream flowing from said cooling coil means;

sensing means disposed downstream of said reheat coil means for sensing the relative humidity of the reheated airstream flowing from said reheat coil means and generating a humidity signal reflective of said sensed relative humidity;

conduit means connecting said precooling and reheat coil means for communicating a working fluid flow through a closed loop circuit comprising said precooling coil means and said reheat coil means;

pump means for controlledely motivating the working fluid flow through said closed loop circuit at a controlled flow rate responsive to said humidity signal; and

,

means for selectively introducing thermal energy into said working fluid flow responsive to i) said humidity signal and ii) said pump means motivating the working fluid flow at a predefined maximum controlled flow rate.

4. The humidity control apparatus according to claim 3 wherein said means for selectively introducing thermal energy into said working fluid flow comprises:

thermal energy storage means for storing thermal energy;

means disposed downstream of said pump means and in said closed loop circuit for dividing said working fluid flow into at least two partial parallel fluid flows comprising i) a bypass fluid flow and ii) a heated fluid flow passing through said thermal energy storage means; and

,

metering means disposed in said closed loop circuit upstream of said reheat coil means for receiving said bypass fluid flow at a first inlet port and said heated fluid flow at a second inlet port and selectively metering the received fluid flows for exhaust at an exhaust port connected to said conduit means.

5. A method of heating a supply airstream into a conditioned space from a return airstream and downstream of a cooling coil of a typical air conditioning system operating in a space dehumidification mode for dehumidifying the conditioned space responsive to a humidity sensor in the conditioned space, the method comprising the steps of:

storing heat energy in a thermal energy storage tank;

sensing the temperature of the conditioned space;

selectively circulating a working fluid at a controlled flow rate from a precooling coil in the return airstream of the air conditioning system directly to a reheat coil in said supply airstream when said sensed temperature is below a first predetermined set point; and

,

selectively circulating the working fluid from the precooling coil through the thermal energy storage tank and the reheat coil in series combination when said controlled flow rate is at a predetermined maximum rate and said sensed temperature is below the first predetermined set point.

6. The method according to claim 5 further comprising the steps of recovering waste thermal energy from said air conditioning system and storing the recovered waste thermal energy in said thermal energy storage tank.

7. A method of controlling the relative humidity of a supply airstream into a conditioned space from a return airstream and downstream of a cooling coil of a typical air conditioning system operating in a space cooling mode for cooling the conditioned space responsive to a dry bulb temperature sensor in the conditioned space, the method comprising the steps of:

storing heat energy in a thermal energy storage tank;

sensing the relative humidity of the supply airstream;

selectively circulating a working fluid at a controlled flow rate from a precooling coil in the return airstream of the air conditioning system directly to a reheat coil in said supply airstream when said sensed relative humidity is above a first predetermined set point; and

,

selectively circulating the working fluid from the precooling coil through the thermal energy storage tank and the reheat coil in series combination when said controlled flow rate is at a predetermined maximum rate and said sensed relative humidity is above the first predetermined set point.

8. The method according to claim 7 further comprising the steps of recovering waste thermal energy from said air conditioning system and storing the recovered waste thermal energy in said thermal energy storage tank.

9. An apparatus for controlling the relative humidity of an airstream supplied into a temperature conditioned space downstream of an air conditioning cooling coil, the apparatus comprising:

control means for controlling the apparatus according to a predetermined control method;

precooling means in said airstream for precooling the airstream upstream of said cooling coil;

reheating means in said airstream for reheating the airstream downstream of said cooling coil;

connecting means for connecting said precooling means and said reheating means in a series closed loop;

humidity sensing means in the airstream downstream of the reheating means and connected to said control means for i) sensing the relative humidity of the airstream between said reheating means and said temperature conditioned space and ii) generating a humidity signal representing the sensed humidity;

working fluid pump means responsive to said control means for selectively pumping a working fluid through said series closed loop when said humidity signal is at a predetermined level, the working fluid pump means having an inherent maximum pumping rate;

thermal energy storage tank means in fluid communication with said connecting means for storing thermal energy therein; and

,

regulating means connected to said connecting means and said thermal energy storage tank means responsive to said control means for selectively regulating a flow of said working fluid through said series closed loop and said thermal energy storage tank means when said working fluid pump means is pumping at said maximum pumping rate and said humidity signal is at said predetermined level.

10. An apparatus for controlling the temperature of an airstream supplied into a moisture conditioned space downstream of an air conditioning cooling coil, the apparatus comprising:

control means for controlling the apparatus according to a predetermined control method;

precooling means in said airstream for precooling the airstream upstream of said cooling coil;

reheating means in said airstream for reheating the airstream downstream of said cooling coil;

connecting means for connecting said precooling means and said reheating means in a series closed loop;

temperature sensing means in the conditioned space downstream of the reheating means and connected to said control means for i) sensing the temperature of the conditioned space downstream of said reheating means and ii) generating a temperature signal representing the sensed temperature;

working fluid pump means responsive to said control means for selectively pumping a working fluid through said series closed loop when said temperature signal is at a predetermined level, the working fluid pump means having an inherent maximum pumping rate;

thermal energy storage tank means in fluid communication with said connecting means for storing thermal energy therein; and

,

regulating means connected to said connecting means and said thermal energy storage tank means responsive to said control means for selectively regulating a flow of said working fluid through said series closed loop and said thermal energy storage tank means when said working fluid pump means is pumping at said maximum pumping rate and said temperature signal is at said predetermined level.