Outdoor Air System Pressure Modulation for 45°F Dew Point Control
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Solution Overview
Problem
Existing air conditioning systems struggle to deliver air at a dew point temperature lower than 55° F, which can lead to discomfort and inefficiencies in maintaining desired humidity and temperature levels, especially in spaces requiring lower dew points for comfort and energy efficiency.
Innovation Solution
A climate-control system incorporating a refrigeration circuit with a compressor, condenser, expansion valve, evaporator coil, and a hot gas reheat unit, along with pressure monitoring and modulation capabilities, to deliver air at a dew point temperature of 45° F or lower, ensuring continuous modulation of compressor capacity and airflow to maintain consistent conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If existing air conditioning systems are used, then they can cool and dehumidify air, but they cannot deliver air at dew point temperatures lower than 55° F
Solution Approach 1:
The system divides the air conditioning function into separate components: a dedicated dehumidification coil for moisture removal and a separate heating coil for temperature adjustment. This segmentation allows independent control of humidity and temperature, enabling the system to achieve dew points below 55° F while maintaining reliable humidity control.
Solution Approach 2:
The patent introduces a hot gas reheat unit as an intermediary component between the cooling coil and the space. This intermediary allows the system to deliver cold, dry air at low dew points while reheating it to prevent over-cooling and maintain comfortable conditions, thus resolving the contradiction between achieving low dew points and maintaining reliable humidity control.
2Temperature
If dew point temperature is reduced below 55° F, then humidity control improves, but ice buildup may occur
Solution Approach 1:
The system performs preliminary dehumidification by removing moisture from air before it reaches temperatures where ice buildup could occur. The dedicated dehumidification coil operates at low temperatures to achieve low dew points, while the subsequent heating coil warms the air to prevent freezing, thus preventing ice buildup while maintaining improved humidity control.
Solution Approach 2:
The patent changes the temperature parameter dynamically by using a two-stage process: first cooling to a low temperature for dehumidification, then reheating to a higher temperature to prevent ice formation. This parameter change allows the system to achieve low dew points without the harmful effect of ice buildup.
3Ease of operation
If traditional systems are used, then they can maintain basic temperature levels, but they cannot achieve desired humidity settings efficiently
Solution Approach 1:
The system incorporates humidity sensors and control mechanisms that provide feedback to adjust the operation of the dehumidification coil and heating coil. This feedback control allows the system to maintain precise humidity settings while optimizing energy usage by adjusting coil operation based on actual humidity levels rather than operating at fixed settings.
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 maintains a 45° F dew point temperature, enhancing comfort and energy efficiency by reducing humidity fluctuations and preventing ice buildup, while accommodating various space types and load conditions, outperforming traditional systems in achieving desired humidity and temperature settings.
Implementation Method 1
a refrigeration circuit with a compressor, condenser, expansion valve, evaporator coil
Implementation Method 2
a hot gas reheat unit positioned between the at least one compressor and the condenser
Data Source
AI summary
A dedicated outdoor air system (DOAS) includes an outdoor unit providing a temperature at a set dry bulb temperature and dew point temperature in a wide variety of outdoor air conditions. The DOAS monitors and modulates suction pressure and head pressure in order to maintain a dew point temperature of 45° F. for supplied air. Furthermore, the DOAS includes a hot gas reheat coil, allowing the system to heat the air to 73° F. before supplying the air to a space, even where outdoor air temperature is lower than 73° F. In one embodiment, the DOAS includes an energy recovery ventilator (ERV) in order to precondition the air to decrease the amount of energy needed to operate the DOAS in some conditions.