HVAC Compressor Cycling Using Air Temperature Feedback
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Solution Overview
Problem
HVAC systems face high energy consumption due to inefficiencies in transferring cooling effects from refrigerant to chilled water and then to air, leading to increased running costs and thermal comfort challenges, especially in large area and district cooling applications.
Innovation Solution
A HVAC system that uses in-flow and out-flow air temperature sensors to control compressors, turning them off when all return air temperatures are lower than a predetermined temperature for a period and turning them on when necessary, to optimize energy usage and thermal comfort in high heat load areas, while maintaining continuous airflow and refrigerant circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If compressors are continuously operated to maintain cooling in HVAC systems, then thermal comfort is ensured, but energy consumption increases significantly
Solution Approach 1:
The patent implements periodic operation of compressors by switching them on and off based on temperature conditions. The control unit monitors return air temperatures from multiple FCUs and activates compressors only when needed, rather than continuous operation. This periodic action maintains thermal comfort while significantly reducing energy consumption, achieving energy savings of 18.6%-32% as demonstrated in test sites.
Solution Approach 2:
The system applies local quality by monitoring return air temperatures from individual FCUs in different rooms and making compressor control decisions based on local temperature conditions. The control unit evaluates temperature data from specific locations (in-flow and out-flow air temperature sensors) to determine compressor operation, allowing targeted cooling only where needed rather than uniform system-wide cooling.
2Use of energy by moving object
If compressors are turned off to reduce energy consumption, then energy efficiency improves, but thermal comfort may deteriorate
Solution Approach 1:
The patent employs feedback control by continuously monitoring return air temperatures from multiple FCUs and using this information to control compressor operation. The control unit receives temperature data from in-flow and out-flow air temperature sensors, compares it against predetermined thresholds, and adjusts compressor operation accordingly. This feedback mechanism ensures thermal comfort is maintained while optimizing energy efficiency, as the system responds dynamically to actual cooling needs.
Solution Approach 2:
The system applies preliminary action by maintaining cooling in advance when heat load increases are anticipated. The control unit monitors temperature trends and activates compressors before thermal comfort deteriorates, ensuring cooling is already available when needed. This proactive approach prevents temperature rise while avoiding unnecessary compressor operation during adequate cooling periods.
3Temperature
If cooling is provided to all areas uniformly, then thermal comfort is maintained throughout the building, but energy consumption increases due to cooling low heat load areas
Solution Approach 1:
The patent implements local quality by monitoring and responding to temperature conditions in specific locations rather than applying uniform cooling system-wide. The control unit evaluates return air temperatures from individual FCUs in different rooms and activates compressors based on local cooling needs. This allows the system to provide cooling only to areas that require it, reducing energy consumption while maintaining thermal comfort where needed.
Solution Approach 2:
The system applies partial action by providing cooling only to the extent necessary based on actual heat load conditions. Rather than continuously cooling all areas uniformly, the compressors operate partially - activating only when return air temperatures indicate cooling is needed in specific zones. This partial operation reduces energy consumption by avoiding excessive cooling in low heat load areas while maintaining adequate cooling where required.
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 approach significantly reduces energy consumption and running costs by balancing thermodynamic and hydraulic work, achieving energy savings of 18.6%-32% compared to conventional systems, as demonstrated in test sites like supermarkets and academic institutions.
Implementation Method 1
A HVAC system that uses in-flow and out-flow air temperature sensors to control compressors
Implementation Method 2
a plurality of compressors and condensers that generate high pressure refrigerant to cool
Implementation Method 3
the cooling effect from the refrigerant is first transferred to the chilled water
Implementation Method 4
which is then used to chill the air used for cooling a room
Data Source
Figure 1
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AI summary
A heating, ventilation and air conditioning system (200) reduces energy consumption in a building (202) by turning on and off all compressors (212, 214, 216). The HVAC system(200) includes a plurality of in-flow air temperature sensors (232, 234, 236) and out-flow air temperature sensors (242, 244, 246) that respectively measure return air temperatures at inlets and supply air temperatures at outlets of fan coil units (222, 224, 226) located in rooms (203, 205, 207) of the building (202). The HVAC system (200) turns on and off all the compressor (212, 214, 216) based on the return air temperatures and the supply air temperatures.