Duct pressure synthesis for air distribution system

• US 5,167,366 A
• Filed: 03/28/1991
• Issued: 12/01/1992
• Est. Priority Date: 03/28/1991
• Status: Expired due to Fees

• Current Assignee: Carrier Corporation (Carrier Global Corporation)
• Original Assignee: Carrier Corporation (Carrier Global Corporation)
• Inventors: Desmarais, Brett A., Gilbert, Jeffrey S.
• Primary Examiner(s): Wayner, William E.
• Application Number:
  US07/676,502
• Time in Patent Office: 614 Days
• Field of Search: 236/49.3, 236/49.4, 454/73, 454/75, 73/700, 73/714
• US Class Current: 236/49.3
• CPC Class Codes: F24F 11/74 for controlling air flow rate or air velocity
• CPC Class Codes: F24F 13/16 built up of parallelly-movable plates
• 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: G05D 23/1925 using a combination of auxiliary electric and non-electric power

Abstract

An air terminal flow detection scheme in an air distribution system effective for developing static pressure indications of the plenum of the air terminal from change in the flow through the air terminal over the period of time of the change.

Claims

1. An apparatus for determining the static pressure in a plenum of an adjustable air terminal of an air distribution system having at least one adjustable air terminal in the plenum for varying the volume of air into a space, comprising:

means for sensing the temperature of space;

means for setting the set point of the desired temperature of the space;

means for adjusting the air flow through the terminal into the space to adesired air flow F_d responsive to the difference between the sensed temperature in the space and set point for the space whereby said means for adjusting the air flow is dependent upon the static pressure in the plenum for the adjustment;

means for measuring the initial air flow F_i through the terminal at an initial time t_i and for measuring the time for the air flow through the terminal to reach the desired flow t_d ; and

means for converting the measured difference between the desired air flow F_d and the initial air flow F_i, and the initial time t_i and the time to reach the desired flow t_d to the static pressure P in the plenum of the air terminal.

2. The apparatus as setforth in claim 1 wherein said converting means employs the relationship P=K×

df/dt, wherein P indicates the air distribution system static pressure, K indicates a constant of proportionality, dF indicates the difference between the desired air flow F_d and the initial air flow F_i, and dt indicates the difference betwen the time at the desired flow t_d and the initial time t_i.

3. The apparatus as setforth in claim 2 further comprising:

means for providing an indication of said static pressure from said converting means.

4. A method of determining the static pressure in a plenum of an adjustable air terminal of an air distribution system having at least one adjustable air terminal, the at least one adjustable air terminal having a variable volume adjustment means dependent upon the static pressure in the plenum for varying the volume of air into a space, comprising the steps of:

determining the actual initial air flow F_i through the terminal at an initial time t_i ;

adjusting the air flow through the terminal to a desired air flow F_d in response to a space condition;

determining the time for the air flow through the temrinal to reach the desired flow t_d from the initial time t_i ; and

converting the difference between the determined desired air flow F_d and the actual intial air flow F_i, and the initial time t_i and the time to reach the desired flow t_d into a measure of the static pressure P in the plenum of the air terminal.

5. The method of determining the static pressure as setforth in claim 4 wherein the static pressure P is calculated according to the relationship:

space="preserve" listing-type="equation">P=K×

(f.sub.d -F.sub.i)/(t.sub.d -t.sub.i)

wherein K is a constant of proportionality of the flow through the adjustable air terminal.