Heat Pump Blower Control for Stable Leaving-Air Temperature
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Solution Overview
Problem
Conventional heat pump systems fail to maintain comfortable leaving air temperatures during heating mode, especially when ice forms on the outdoor heat exchange coil, leading to reduced heating capacity and occupant discomfort, as they do not adequately adjust airflow in response to changing outdoor temperatures and ice formation.
Innovation Solution
A method and apparatus that sense the temperature of a heat exchanger and compressor speed to determine variable blower speeds for the air blower, adjusting airflow across a second heat exchanger to maintain optimal leaving air temperature, using a controller with a memory to select blower speeds based on compressor speed and heat exchanger temperature, and storing these in an airflow lookup table for efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If constant airflow rate is used in conventional heat pump systems, then the system operates simply with fixed airflow, but the leaving air temperature drops when heating capacity decreases due to low outdoor temperature or ice formation, causing occupant discomfort
Solution Approach 1:
The patent applies dynamics by transitioning from fixed airflow to variable airflow control. The system dynamically adjusts the blower motor speed based on real-time heating capacity measurements, allowing the airflow rate to change in response to varying outdoor conditions and ice formation, thereby maintaining stable leaving air temperature.
Solution Approach 2:
The patent implements feedback control by continuously measuring the actual heating capacity of the heat pump system and using this information to adjust the airflow rate. The controller monitors system performance and modifies blower speed to compensate for capacity changes, ensuring the leaving air temperature remains within comfortable ranges.
2Temperature
If variable airflow is used based on outdoor ambient temperature, then the supply air temperature can be maintained at a constant level, but the airflow does not adjust when ice forms on the outdoor heat exchange coil, causing leaving air temperature to drop
Solution Approach 1:
The patent enhances feedback control by not only monitoring outdoor ambient temperature but also directly measuring the actual heating capacity of the system. This dual-feedback approach allows the controller to detect capacity reductions due to ice formation and adjust airflow accordingly, maintaining reliable leaving air temperature even when traditional temperature-based control fails.
Solution Approach 2:
The system performs self-adjustment by automatically modifying airflow based on measured heating capacity without requiring manual intervention. The controller continuously adapts the blower speed to match the actual system capacity, enabling the system to self-correct for performance degradation from ice accumulation.
3Temperature
If airflow rate is increased to maintain leaving air temperature when heating capacity drops, then occupant comfort is improved, but energy consumption increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the airflow rate parameter based on the measured heating capacity. Instead of using fixed or solely temperature-based airflow settings, the system modifies the airflow parameter in real-time to match actual system capacity, optimizing both comfort and energy efficiency.
Solution Approach 2:
The patent creates an optimized operational environment by matching airflow to actual heating capacity, preventing energy waste. By adjusting airflow to correspond with the heat pump's actual output, the system avoids the energy inefficiency of moving excess air that would otherwise require heating, thereby reducing blower and heating energy consumption.
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
This solution effectively maintains comfortable leaving air temperatures by adjusting airflow in response to outdoor heat exchanger and compressor speed, enhancing occupant comfort and system efficiency, even during low outdoor temperatures and ice formation, by optimizing blower speeds and airflow rates.
Implementation Method 1
a first heat exchanger that is in fluid communication with both the compressor and a second heat exchanger... to heat the airflow
Implementation Method 2
a compressor that is adapted to operate at a compressor speed to compress the refrigerant
Implementation Method 3
an air blower that is adapted to operate at one or more variable blower speeds... to direct a flow of air across a second heat exchanger
Data Source
AI summary
An apparatus and method for controlling the heating of an airflow. According to certain embodiments, the temperature of an outdoor heat exchanger and the speed of a compressor are used to determine a blower speed for a variable speed indoor air blower. The selected blower speed may facilitate a flow of air across a second, indoor heat exchanger at an indoor volumetric flow rate that heats the airflow to a leaving air temperature. The leaving air temperature may at least seek to attain the temperature of a variable target leaving air temperature that is adjusted based on changes in outdoor ambient temperatures. Additionally, according to certain embodiments, the blower speed may be based on an indoor volumetric airflow rate that is determined, at least in part, on a determined system heating capacity and a temperature at the outdoor heat exchanger.