Cooling system and corresponding operating method
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Solution Overview
Problem
Cooling systems with microchannel tubes in their heat exchangers face challenges in providing sufficient storage for refrigerant during pump down operations, as the internal volume of these heat exchangers is relatively small, which can lead to issues like evaporator water tube freezing due to refrigerant migration at low ambient conditions.
Innovation Solution
A cooling system design that includes a heat exchanger with microchannel tubes and fins, fluidly connected to a volume configured to store refrigerant, utilizing a flow control device to manage refrigerant storage and flow, ensuring adequate storage capacity during pump down operations without affecting normal cooling mode operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If microchannel tubes are used in heat exchanger construction, then heat exchange efficiency is improved, but refrigerant storage volume is insufficient
Solution Approach 1:
The heat exchanger is divided into two distinct functional zones: a first region with microchannel tubes for high-efficiency heat exchange, and a second region with larger channel dimensions for refrigerant storage. This segmentation allows each zone to optimize its specific function without compromising the other.
Solution Approach 2:
Different regions of the heat exchanger are designed with different local qualities - the first region has small channel dimensions optimized for heat transfer, while the second region has larger channel dimensions optimized for storage capacity. This local differentiation resolves the contradiction between efficiency and storage volume.
2Object-affected harmful factors
If refrigerant is removed from evaporator during pump down operation, then water tube freezing is prevented, but refrigerant storage capacity is insufficient
Solution Approach 1:
The heat exchanger is pre-designed with a dedicated storage region that can accommodate refrigerant during pump down operations. This preliminary structural preparation ensures that when refrigerant needs to be removed from the evaporator to prevent freezing, there is adequate pre-configured space to store it safely.
3Volume of moving object
If heat exchanger internal volume is reduced for compact design, then system size is minimized, but refrigerant storage capability is compromised
Solution Approach 1:
The heat exchanger employs a nested configuration where multiple channels are arranged in parallel within a compact footprint. The first region with microchannel tubes is nested alongside the second region with larger channels, allowing both high heat exchange efficiency and adequate storage capacity within a minimized overall volume.
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 design effectively addresses the refrigerant storage challenge, minimizing the risk of evaporator water tube freezing and maintaining system reliability, with the ability to integrate seamlessly into existing systems without significant modifications.
Implementation Method 1
heat exchanger, such as for example, a condenser coil constructed with fins and microchannel tubes
Implementation Method 2
heat exchanger is fluidly connected with a volume constructed and configured to store refrigerant
Implementation Method 3
evaporator and out of contact with water tubes in the evaporator
Implementation Method 4
heat exchanger, such as for example, a condenser coil
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A heat exchanger, such as for example, a condenser coil constructed as a fin and microchannel tube is fluidly connected with a volume constructed and configured to store refrigerant in certain operations, such as for example during a pump down operation. The volume is fluidly connected to a fluid port of the heat exchanger, where the fluid port is an inlet (in the cooling mode) to the heat exchanger, such as the high side condensing section of the heat exchanger. The volume receives refrigerant exiting the heat exchanger from the fluid port in a mode other than a cooling mode, e.g., a pump down operation.