Variable Condenser Reheat for AC Dehumidification Without Overcooling
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Solution Overview
Problem
Air conditioning systems with re-heating systems often overcool the air during dehumidification due to a positive Sensible cooling-to-Total cooling ratio, leading to wasted energy and inefficient humidity control.
Innovation Solution
An air conditioning system that includes a vapor compression circuit, an evaporator, an air-reheat heat exchanger, and a control system capable of computing the Sensible cooling-to-Total cooling ratio, allowing for the adjustment of the operation of these components to optimize dehumidification and avoid overcooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the vapor compression circuit and evaporator continue to cool the air to remove excess humidity, then the desired relative humidity is achieved, but the air and space are overcooled resulting in wasted energy
Solution Approach 1:
The system segments the cooling function into two separate heat exchangers: the evaporator for dehumidification and the condenser for reheat. This allows independent control of humidity removal and temperature adjustment, preventing overcooling while maintaining effective dehumidification.
Solution Approach 2:
The condenser acts as an intermediary reheat component between the evaporator and the space. It recovers heat from the refrigerant condensation process to warm the supply air, serving as a mediator that prevents the harmful overcooling effect while preserving the beneficial dehumidification.
2Loss of energy
If the re-heat coil is sized to provide neutral supply air temperature, then overcooling is avoided, but the dehumidification capability is reduced
Solution Approach 1:
The system divides the thermal control functions between two dedicated components: the evaporator handles dehumidification with aggressive cooling, while the condenser provides specialized reheat function. This segmentation allows each component to be optimized for its specific purpose without compromise.
Solution Approach 2:
The system changes the operational parameters of the condenser from traditional cooling assistance to active reheat mode. By controlling the condenser to add heat rather than remove it, the system transforms a potential source of overcooling into a solution that enables both effective dehumidification and energy efficiency.
3Temperature
If cooling priority is used to satisfy the cooling requirement first, then the temperature setpoint is met, but enhanced dehumidification is delayed resulting in more energy consumption
Solution Approach 1:
The system inverts the traditional control sequence by implementing humidity priority rather than temperature priority. The evaporator operates continuously to remove humidity regardless of temperature conditions, and the condenser compensates for overcooling in real-time, enabling faster dehumidification response.
Solution Approach 2:
The evaporator maintains continuous dehumidification action without interruption or delay based on temperature conditions. The dual heat exchanger configuration allows this continuous useful action to proceed while the condenser simultaneously manages temperature, eliminating waiting periods and reducing 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
The system effectively reduces energy waste by precisely controlling the dehumidification process, ensuring the air is conditioned to the desired relative humidity without overcooling, thereby optimizing energy usage.
Implementation Method 1
the evaporator receives refrigerant from the vapor compression circuit and is adapted to provide a cooled stream of air to the space
Implementation Method 2
an air-reheat heat exchanger positioned to receive the cooled stream of air
Implementation Method 3
a condenser, and an expansion device; an evaporator
Data Source
AI summary
An air conditioning system comprising an air mover for circulating air to a space; a vapor compression circuit including a compressor, a condenser, and an expansion device; an evaporator; an air-reheat heat exchanger; and a control system. In one embodiment, the evaporator receives refrigerant from the vapor compression circuit and provides a cooled stream of air to the space. The air-reheat heat exchanger is positioned to receive the cooled stream of air. In one embodiment, the vapor compression circuit, the evaporator, and the air-reheat heat exchanger are operable in combination to provide a plurality of modes of operation. In a preferred embodiment, the control system is configured to compute a Sensible cooling-to-Total cooling (S/T) process ratio and to control an operation of at least one of the vapor compression circuit, the evaporator, and the air-reheat heat exchanger. A method of manufacturing the air conditioning system is also provided.