Variable-Speed HVAC Control for Higher Latent Cooling Capacity
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Solution Overview
Problem
HVAC systems face challenges in optimizing discharge air temperature and compressor speed during dehumidification, leading to inefficiencies in latent capacity and increased energy consumption.
Innovation Solution
A variable-speed compressor and circulation fan system controlled by a controller that adjusts speeds based on temperature thresholds to lower discharge air temperature, maintaining a favorable sensible-to-total heat ratio and enhancing dehumidification effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the compressor speed is increased to improve cooling capacity, then the cooling effect is enhanced, but the discharge air temperature becomes too high which reduces dehumidification effectiveness
Solution Approach 1:
The patent applies dynamics by implementing variable-speed control for both the compressor and circulation fan, allowing the system to continuously adjust operating parameters based on real-time temperature feedback. The controller modulates compressor speed and fan speed independently to maintain optimal discharge air temperature while preserving cooling capacity, resolving the contradiction between high power output and temperature control.
2Speed
If the circulation fan speed is increased to improve air flow, then the cooling distribution is enhanced, but the discharge air temperature increases which harms dehumidification
Solution Approach 1:
The patent implements feedback control by using temperature sensors to continuously monitor discharge air temperature and using this information to adjust circulation fan speed. When the discharge air temperature approaches or exceeds the threshold, the controller reduces fan speed to prevent temperature rise, thereby maintaining dehumidification effectiveness while still providing adequate air flow for cooling distribution.
3Productivity
If the HVAC system operates at high capacity to meet cooling demand, then the cooling effect is sufficient, but the latent capacity is reduced due to high discharge air temperature
Solution Approach 1:
The patent applies parameter changes by independently adjusting the operating parameters of the compressor and circulation fan rather than controlling them as a fixed ratio. By changing the speed parameters dynamically based on discharge air temperature feedback, the system maintains high total cooling capacity while specifically optimizing latent capacity through controlled discharge air temperature, ensuring both cooling demand satisfaction and dehumidification performance.
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 solution increases latent cooling capacity, reduces energy consumption, and prevents re-evaporation of moisture, improving dehumidification efficiency and extending HVAC system run times.
Implementation Method 1
the controller is configured to modulate at least one of a speed of the variable-speed compressor and the variable-speed circulation fan to lower a discharge air temperature
Implementation Method 2
an evaporator coil and a metering device fluidly coupled to the evaporator coil. The HVAC system includes a variable-speed circulation fan for circulating air around the evaporator coil and a condenser coil fluidly coupled to the metering device
Data Source
AI summary
An HVAC system includes an evaporator coil and a metering device. The HVAC system includes a variable-speed circulation fan and a condenser coil fluidly coupled to the metering device. A variable-speed compressor is fluidly coupled to the condenser coil and the evaporator coil. A controller is operatively coupled to the variable-speed compressor and the variable-speed circulation fan. A second temperature sensor is disposed in an enclosed space. The second temperature sensor measures temperature of the enclosed space and transmits the temperature of the enclosed space to the controller. The controller determines if the temperature of the enclosed space is below a minimum threshold. Responsive to a determination that the temperature of the enclosed space is below the minimum threshold, the controller modulates at least one of a speed of the variable-speed compressor and the variable-speed circulation fan to lower a discharge air temperature.