Heat Pump Intercooler Layout Using Outdoor Airflow
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Solution Overview
Problem
Conventional refrigerant systems with two-stage compressors face high discharge temperatures due to high operating pressures and transcritical cycles, necessitating additional cooling components for intercoolers, which are costly and less desirable, especially with CO2 refrigerants.
Innovation Solution
An intercooler is positioned upstream of the outdoor heat exchanger, utilizing ambient airflow for cooling, eliminating the need for additional circuitry and components, and allowing the outdoor fan to cool the intercooler in both cooling and heating modes, thereby reducing inter-stage refrigerant temperature and enhancing system efficiency and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an intercooler is added to cool refrigerant between compression stages, then compressor discharge temperature is reduced and system reliability is improved, but additional components and circuitry are required which increases device complexity and cost
Solution Approach 1:
The outdoor heat exchanger serves dual functions: as a condenser/gas cooler for refrigerant cooling and as an intercooler for intermediate refrigerant cooling between compression stages. The outdoor fan also performs dual function by cooling both the outdoor heat exchanger and the intercooler, eliminating the need for separate cooling components.
Solution Approach 2:
The intercooler is merged with the outdoor heat exchanger assembly, combining two cooling functions into a single integrated structure. This merging eliminates the need for separate intercooler components and their associated circuitry, reducing device complexity while maintaining reliability benefits.
2Temperature
If additional components and circuitry are added to cool refrigerant in the intercooler, then inter-stage refrigerant temperature is reduced, but manufacturing cost and device complexity increase
Solution Approach 1:
The outdoor heat exchanger and outdoor fan are made multi-functional, serving both their original cooling purposes and the additional intercooling function. This eliminates the need for separate intercooler components, reducing manufacturing cost while effectively reducing inter-stage refrigerant temperature.
3Productivity
If a two-stage compressor is used to enhance capacity and efficiency, then compression ratio is improved, but discharge temperature becomes extremely high exceeding safety limits
Solution Approach 1:
The compression process is segmented into two stages with an intermediate cooling step. The intercooler divides the compression process, allowing intermediate cooling of the refrigerant between stages, which enables higher overall compression ratios while keeping discharge temperatures within safe limits through staged compression and cooling.
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 reduces compressor discharge temperature, increases cooling potential, and improves heating cycle efficiency by pre-heating the air stream, allowing for optimal performance in both modes without additional components, particularly beneficial for CO2 systems with high pressures and transcritical cycles.
Implementation Method 1
an intercooler is provided between the two compression stages... the intercooler is preferably subjected to the ambient airflow... the cooling in the intercooler is preferably provided by the circuitry and components that are already part of the refrigerant system
Implementation Method 2
an outdoor fan that passes air over the outdoor heat exchanger also cools the intercooler
Implementation Method 3
an outdoor fan that passes air over the outdoor heat exchanger also cools the intercooler
Implementation Method 4
the same outdoor fan cools the intercooler but now in conjunction with the air stream passing over the evaporator... the heat rejected by the intercooler
Data Source
AI summary
A heat pump refrigerant system is provided with at least two sequential stages of compression. An intercooler is positioned intermediate the two stages. The refrigerant flowing through the intercooler. is cooled by a secondary fluid such as ambient air. The intercooler is positioned to be in a path of air flow passing over an outdoor heat exchanger, and preferably upstream of the outdoor heat exchanger, in relation to this air flow. Benefits with regard to efficiency and capacity are achieved due to proposed system configuration in both heating and cooling modes of operation, while no additional circuitry or components are required to provide the intercooler function for the heat pump refrigerant system. This invention is particularly important for the CO2 heat pump refrigerant systems operating in the transcritical cycle.