Hot Gas Reheat Circuit Control to Minimize Refrigerant Hold-Up
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Solution Overview
Problem
Space conditioning systems face inefficiencies in managing humidity levels, as they expend significant energy cooling and then reheating air to meet both humidity and temperature requirements, leading to a high latent heat load.
Innovation Solution
A space conditioning system with a compressor, condenser, and hot gas reheat section, featuring modulating valves and parallel refrigerant circuits, allows for adjustable refrigerant flow to optimize energy recovery by directing refrigerant through different paths and volumes within the hot gas reheat section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the supply air temperature is reduced to remove humidity through condensation, then humidity removal effectiveness is improved, but energy efficiency deteriorates due to subsequent reheating requirements
Solution Approach 1:
The patent converts the harmful effect of wasted latent heat into a beneficial resource by using the cold refrigerant lines (which would normally be discarded) as a heat exchange medium to pre-cool the supply air during reheating, thereby reducing the energy required for reheating while maintaining humidity removal effectiveness
Solution Approach 2:
The patent recovers the latent heat that would otherwise be discarded during the humidity removal process by using the cold refrigerant lines to pre-cool the supply air, transforming a waste energy stream into a useful cooling source that reduces overall energy consumption
2Use of energy by moving object
If refrigerant flow through the hot gas reheat section is increased to improve energy recovery, then energy efficiency is improved, but liquid refrigerant accumulation increases causing system performance degradation
Solution Approach 1:
The patent implements dynamic control of refrigerant flow through the hot gas reheat section by using an electronically expanded thermal expansion valve that can modulate the refrigerant flow rate in real-time, allowing the system to optimize energy recovery while preventing liquid refrigerant accumulation by adjusting flow conditions dynamically
Solution Approach 2:
The patent changes the refrigerant flow parameters (flow rate, pressure, temperature) by using an electronically expanded thermal expansion valve that can precisely control the refrigerant expansion process, enabling the system to maintain optimal flow conditions that maximize energy recovery while preventing liquid accumulation that would degrade 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
This configuration enhances energy efficiency by allowing for precise control of refrigerant flow, reducing the accumulation of liquid refrigerant in the hot gas reheat section, thereby minimizing refrigerant charge issues and improving system performance.
Implementation Method 1
One or more modulating valves are coupled to an outlet of the compressor to receive compressed vapor refrigerant from the compressor
Implementation Method 2
the desirable dew point temperature is lower than the desirable dry-bulb temperature at which the supply air is to be delivered for occupant comfort. In order to meet both the humidity and the temperature requirements, the supply air is often reheated to a desirable dry-bulb temperature
Implementation Method 3
a condenser, and a hot gas reheat section
Data Source
AI summary
A space conditioning system includes a hot gas reheat section and one or more modulating valves to direct a percentage of refrigerant flow to the hot gas reheat section. The hot gas reheat section includes multiple refrigerant circuits arranged in parallel. A control valve is used to allow the refrigerant to flow through selected ones of the multiple refrigerant circuits in response to the percentage of refrigerant flow directed to the hot gas reheat section, thereby varying the internal volume of the hot gas reheat section available to the refrigerant. Refrigerant charge hold-up within the hot gas reheat section can thereby be minimized.