Intercooler Reheat Layout for Two-Stage CO2 Refrigeration
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Solution Overview
Problem
Refrigerant systems with two-stage compressors, especially those using CO2, face high discharge temperatures due to high operating pressures and transcritical cycles, leading to increased costs and complexity with traditional intercoolers and reheat circuits.
Innovation Solution
Positioning an intercooler downstream of the indoor heat exchanger allows it to provide both intercooler and reheat functions without additional circuitry or components, utilizing existing air-moving devices, and enabling selective activation of these functions on demand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional intercooler is provided between two compression stages, then compressor discharge temperature is reduced and system reliability is improved, but additional components and circuitry are required increasing system complexity and cost
Solution Approach 1:
The patent combines the intercooler and reheat heat exchanger into a single integrated component. The intercooler cools refrigerant between compression stages while simultaneously serving as the reheat heat exchanger that warms air downstream of the evaporator, eliminating the need for separate components and reducing system complexity.
Solution Approach 2:
The heat exchanger performs multiple functions: it acts as an intercooler for the refrigerant compression process and simultaneously as a reheat heat exchanger for the air stream. This multi-functionality reduces the number of components needed while maintaining both intercooling and reheat capabilities.
2Adaptability or versatility
If a reheat circuit is added downstream of the evaporator, then dehumidification capability is enhanced, but additional heat exchanger components are required increasing system complexity
Solution Approach 1:
The patent merges the reheat heat exchanger function with the intercooler component. The same heat exchanger that cools refrigerant between compression stages also serves as the reheat heat exchanger that warms air downstream of the evaporator, eliminating the need for a separate reheat circuit.
Solution Approach 2:
The heat exchanger is designed to perform dual functions: intercooling the refrigerant and reheating the air stream. This multi-functionality provides dehumidification capability through the reheat function while avoiding additional components.
3Loss of energy
If CO2 refrigerant is used in transcritical cycle, then system efficiency is improved, but discharge temperature becomes extremely high requiring intercooling
Solution Approach 1:
The patent integrates the intercooler with the reheat heat exchanger, allowing the CO2 refrigerant to be cooled between compression stages while utilizing the air stream from the evaporator. This combined approach maintains the efficiency benefits of CO2 transcritical cycles while managing the high discharge temperatures through intercooling.
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 system capacity and efficiency by reducing compressor discharge temperature, allowing for higher cooling potential and improved reliability, particularly in transcritical CO2 cycles, while reducing costs and complexity.
Implementation Method 1
an intercooler heat exchanger also provides a reheat function
Implementation Method 2
The intercooler is placed in the air stream moving over an indoor heat exchanger
Implementation Method 3
an intercooler heat exchanger also provides a reheat function
Data Source
AI summary
A refrigerant system is provided with at least two stages of compression connected in series. An intercooler is positioned intermediate the two stages and is cooled by an indoor air stream. The intercooler is positioned to be in a path of air flow passing over an indoor heat exchanger, and preferably downstream of the indoor heat exchanger, in relation to this airflow. The intercooler cools the refrigerant flowing between the two compression stages as well as provides the reheat function. Benefits with regard to system performance (efficiency, capacity and reliability) are achieved with no additional circuitry or components required to provide the intercooler and reheat functions. This invention is particularly important for the CO2 refrigerant systems operating in the transcritical cycle. Methods of control are presented for both the intercooler and reheat functions.