Method of detecting short cycling of air discharged by a refrigeration unit
First Claim
1. A method of monitoring the operation of a refrigeration unit which includes a return air inlet and a discharge air outlet in air flow communication with a conditioned space, with the refrigeration unit conditioning air returning from the conditioned space via the air inlet and discharging conditioned air back into the conditioned space via the discharge air outlet, characterized by the steps of:
- detecting a short cycling condition wherein air from the discharge air outlet returns prematurely to the return air inlet,said detecting step including the steps of;
measuring the temperatures DA and RA of the discharge air and return air, respectively,detecting changes of the discharge air temperature DA and the return air temperature RA over a predetermined period of time,comparing a detected change of the temperature DA of the discharge air with a first constant,comparing a detected change of the temperature RA of the return air with a second constant,and indicating that air flow in the conditioned space is proper in response to predetermined results of the comparison steps.
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Abstract
A method of monitoring a refrigeration unit including detecting premature return of air discharged into a conditioned space, and distinguishing this "short cycling" problem from a refrigeration capacity problem. The method includes determining the rates of change of the temperatures DA and RA of the discharge air and return air, respectively, during temperature pull down of the conditioned space, and comparing the rates of change with predetermined constants selected to detect a short cycling of the discharge air. When the rates of change do not fit a normal temperature pull down, the differential ΔD between the temperatures DA and RA of the discharge air and return air is determined and compared with a third constant. Predetermined results of the comparisons of the rates of changes of DA and RA, and the temperature difference ΔD with the first, second and third constants, respectively, are utilized to identify proper air flow in conditioned space, to indicate a problem with air flow in conditioned space, and to indicate that refrigeration capacity should be checked.
41 Citations
17 Claims
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1. A method of monitoring the operation of a refrigeration unit which includes a return air inlet and a discharge air outlet in air flow communication with a conditioned space, with the refrigeration unit conditioning air returning from the conditioned space via the air inlet and discharging conditioned air back into the conditioned space via the discharge air outlet, characterized by the steps of:
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detecting a short cycling condition wherein air from the discharge air outlet returns prematurely to the return air inlet, said detecting step including the steps of; measuring the temperatures DA and RA of the discharge air and return air, respectively, detecting changes of the discharge air temperature DA and the return air temperature RA over a predetermined period of time, comparing a detected change of the temperature DA of the discharge air with a first constant, comparing a detected change of the temperature RA of the return air with a second constant, and indicating that air flow in the conditioned space is proper in response to predetermined results of the comparison steps. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of monitoring the operation of a refrigeration unit which includes a return air inlet and a discharge air outlet in air flow communication with a conditioned space, with the refrigeration unit conditioning air returning from the conditioned space via the air inlet and discharging conditioned air back into the conditioned space via the discharge air outlet, characterized by the steps of:
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detecting a short cycling condition wherein air from the discharge air outlet returns prematurely to the return air inlet, said detecting step including the steps of; measuring the temperatures DA and RA of the discharge air and return air, respectively, detecting changes of the discharge air temperature DA and the return air temperature RA over a predetermined period of time, comparing a detected change of the temperature DA of the discharge air with a first constant, comparing a detected change of the temperature RA of the return air with a second constant when the detected change of the temperature DA of the discharge air exceeds the first constant, and indicating that air flow in the conditioned space is proper when the detected change of the temperature RA of the return air is less than the second constant. - View Dependent Claims (14)
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15. A method of monitoring the operation of a refrigeration unit which includes a return air inlet and a discharge air outlet in air flow communication with a conditioned space, with the refrigeration unit conditioning air returning from the conditioned space via the air inlet and discharging conditioned air back into the conditioned space via the discharge air outlet, characterized by the steps of:
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measuring the temperature DA and RA of the discharge air and return air, respectively, determining the change in the temperature DA of the discharge air over a first predetermined period of time, comparing the change in the temperature DA of the discharge air with a first constant, continuing the steps of determining the change in the temperature DA of the discharge air, and comparing the change with the first constant, up to a maximum predetermined period of time, when the comparing step at the end of the first predetermined period of time found that the change in temperature DA of the discharge air did not exceed the first constant, determining the change in temperature RA of the return air, when the change in temperature DA is found to exceed the first constant, over the same period of time over which the change in DA was measured, comparing the change in temperature RA with a second constant, and indicating proper air flow when the change in temperature RA is less than the second constant. - View Dependent Claims (16, 17)
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Specification