Dynamic Compressor Delay Control for HVAC Cycling and Energy Use
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Solution Overview
Problem
Conventional HVAC systems lack a simple method to create asymmetrical thermal waveforms without complex programming, and users are not provided a means to adjust compressor delays accessible outside the unit, which can lead to rapid cycling and increased energy consumption.
Innovation Solution
A networked HVAC control system that allows users to dynamically adjust compressor delays through a website interface, using a thermostat with microprocessor control and bi-directional communication, enabling asymmetrical thermal waveforms without changing the displayed setpoint, thereby optimizing energy use and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed compressor delay is implemented to prevent rapid cycling, then system reliability is improved, but energy consumption increases due to extended off-periods
Solution Approach 1:
The patent implements a dynamic compressor delay system that adjusts the delay period based on real-time operating conditions. The microprocessor monitors parameters such as compressor run-time, outdoor temperature, and humidity to calculate an optimal delay value. This resolves the contradiction by making the delay adaptive rather than fixed, protecting the compressor while minimizing unnecessary energy waste during milder conditions.
Solution Approach 2:
The system changes the delay parameter dynamically based on environmental conditions and system state. When outdoor temperatures are extreme or humidity is high, the delay is extended to ensure proper refrigerant flash-off. Under milder conditions, the delay is reduced, allowing more frequent cycling that improves comfort and reduces energy consumption. This parameter adaptation resolves the contradiction between protection and efficiency.
2Device complexity
If hysteresis band is used to prevent rapid cycling, then device complexity is reduced, but energy consumption increases due to inability to create asymmetrical thermal waveforms
Solution Approach 1:
The patent maintains the simple hysteresis band mechanism but adds dynamic control through a microprocessor that adjusts the compressor delay independently. This allows the system to create asymmetrical thermal waveforms by extending the off-period selectively without complicating the basic temperature sensing and switching mechanism. The result is reduced energy consumption while preserving the simplicity of the core control approach.
Solution Approach 2:
The control function is segmented into two independent parts: the hysteresis band for temperature sensing and switching, and the dynamic delay calculator for optimizing the off-period. This segmentation allows each component to perform its function simply while the integrated system achieves advanced energy optimization through the interaction of these separate functions.
3Reliability
If compressor delay is extended to protect against rapid cycling, then reliability is improved, but comfort deteriorates due to temperature oscillations
Solution Approach 1:
The system dynamically adjusts the delay duration based on real-time conditions, extending it only when necessary for compressor protection (such as when outdoor temperatures suggest rapid refrigerant flash-off) and reducing it when conditions allow more frequent cycling. This dynamic adaptation maintains reliability while minimizing the impact on comfort, as the delay is not fixed but responsive to environmental factors.
Solution Approach 2:
The delay parameter is changed based on outdoor temperature and humidity readings. When these parameters indicate high risk of liquid slugging, the delay is extended for protection. When parameters are favorable, the delay is reduced to improve comfort. This conditional parameter adjustment resolves the contradiction between protection and comfort.
4Ease of operation
If fixed delay settings are used, then ease of operation is improved, but adaptability deteriorates due to inability to respond to varying environmental conditions
Solution Approach 1:
The system performs self-adjustment by automatically monitoring environmental conditions and calculating the optimal delay setting without user intervention. The microprocessor reads temperature and humidity sensors, applies the delay calculation algorithm, and adjusts the compressor control accordingly. This maintains ease of operation while achieving high adaptability, as the system serves itself rather than requiring manual reconfiguration.
Solution Approach 2:
The system implements feedback control by continuously monitoring outdoor conditions and using this information to adjust the compressor delay. The feedback loop ensures the delay setting always matches current environmental conditions, providing adaptability without requiring user knowledge or action. This resolves the contradiction by making the system both simple to operate and highly adaptive through automatic feedback-driven adjustment.
Data Source
AI summary
Systems and methods are disclosed for reducing the usage of a ventilation system. For example, one or more of the exemplary systems comprise a thermostatic controller that has at least two settings for the delay occurring between turning the ventilation system off and then turning the system back on. One setting being for a first interval and at least a second setting for a second interval that is longer than the first interval. A processor is in communication with the thermostatic controller and is configured to evaluate one or more parameters including at least the temperature outside the structure conditioned by the ventilation system. The processor is further configured to determine whether to adopt the first interval or the second interval based upon the values of the parameters.