Adaptive Discharge Air Temperature Control for Faster HVAC Cooling
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Solution Overview
Problem
Previous HVAC systems often fail to reach target air temperatures even when they have unused cooling capacity, and are slow to respond to sudden changes in load or setpoint temperature adjustments, particularly when operating separate control loops for blowers and compressors.
Innovation Solution
An adaptive discharge air temperature setpoint is determined by the HVAC system's controller to adjust compressor operation, ensuring faster and more reliable indoor air temperature control by increasing cooling capacity when needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If separate control loops are used for blowers (based on indoor air temperature) and compressors (based on discharge air temperature), then the system structure is simpler and easier to operate, but the system fails to reach target indoor temperatures and is slow to respond to load changes
Solution Approach 1:
The patent combines the blower control loop and compressor control loop into an integrated control system. The controller simultaneously manages both components based on a unified control strategy that considers indoor air temperature, discharge air temperature, and their interrelationships, enabling coordinated operation to reliably reach target temperatures.
Solution Approach 2:
The system implements predictive control by monitoring discharge air temperature as a leading indicator and adjusting compressor operation in advance before the indoor temperature deviation becomes significant. This preliminary action prevents temperature excursions and maintains more stable indoor conditions.
2Ease of operation
If the HVAC system operates with standard discharge air temperature setpoints, then the system operation is straightforward, but the system is slow to provide cooling when there is a sudden change in load or setpoint temperature
Solution Approach 1:
The patent implements dynamic discharge air temperature setpoints that automatically adjust based on system operating conditions, indoor temperature deviations, and load changes. This dynamic adaptation enables the system to respond rapidly to sudden load changes while maintaining ease of operation through automated control.
Solution Approach 2:
The system uses feedback from indoor air temperature sensors and discharge air temperature sensors to continuously adjust compressor and blower operations. This closed-loop feedback mechanism enables rapid response to temperature deviations and load changes while maintaining simple operation through automated control.
3Device complexity
If the HVAC system uses fixed discharge air temperature control, then the control mechanism is simple, but the system may never reach the target indoor temperature even with unused cooling capacity
Solution Approach 1:
The system adjusts discharge air temperature setpoints in advance based on predicted cooling demands and indoor temperature trends. This preliminary adjustment ensures that the system has sufficient cooling capacity available before temperature deviations occur, enabling reliable setpoint achievement without excessive complexity.
Solution Approach 2:
The patent implements a feedback control mechanism that continuously monitors indoor air temperature and discharge air temperature, comparing actual values with target values. Based on the deviations detected, the system automatically adjusts compressor and blower operations to eliminate temperature differences and achieve the desired indoor temperature setpoint.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The adaptive approach allows for quicker and more reliable achievement of comfortable indoor temperatures, overcoming the limitations of previous systems by dynamically adjusting compressor speed based on indoor and discharge air temperature differences.
Implementation Method 1
a flow of air may be cooled via heat transfer with refrigerant
Data Source
AI summary
An HVAC system includes a blower, a variable-speed compressor, an indoor air temperature sensor that measures an indoor air temperature (IAT) of an enclosed space, a discharge air temperature sensor that measures a discharge air temperature (DAT) of the flow of air from an evaporator, and a controller. The controller stores an indoor temperature setpoint and a default discharge air temperature setpoint. The controller receives the IAT and the DAT. The controller determines that the IAT is not within a threshold range of the indoor temperature setpoint. The controller then determines an adaptive discharge air temperature setpoint. The controller determines a compressor speed at which to operate the variable-speed compressor based on the adaptive discharge air temperature setpoint. The controller causes the variable-speed compressor to operate at the determined compressor speed.