VRF Reheater Flow Control for Dehumidified Supply Air Temperature
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Variable refrigerant flow (VRF) systems face challenges in controlling the reheating of overcooled air, leading to discomfort due to inconsistent supply air temperatures, as the fixed ratio of cooling and heating capacities can result in air being too cold or too hot for the space, especially when dehumidification is needed in mild ambient temperatures.
Innovation Solution
The system controls refrigerant flow to a reheater by directing a portion of hot refrigerant from the compressor to the reheater during reheating mode and to the outdoor heat exchanger during non-reheating mode, using a solenoid valve to regulate the refrigerant flow ratio, allowing for precise temperature control of the supply air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the indoor heat exchanger cools air to condense water vapor for dehumidification, then humidity level is reduced, but the air becomes overcooled and too cold for the space
Solution Approach 1:
The patent segments the refrigerant flow into two separate paths using a flow control valve: one path directs refrigerant to the indoor heat exchanger for dehumidification, while the other path directs refrigerant to the reheater for temperature adjustment. This allows independent control of humidity removal and temperature regulation, resolving the contradiction between dehumidification and preventing overcooling
Solution Approach 2:
The patent introduces a reheater as an intermediary component between the compressor and the indoor heat exchanger. The reheater uses a separate refrigerant flow to heat the air that has been overcooled during dehumidification, acting as a mediator that corrects the temperature issue without interfering with the humidity removal process
2Device complexity
If the same refrigerant flow passes through both the indoor heat exchanger and reheater in series, then the system structure is simplified, but the supply air temperature becomes difficult to control and may be too cold or too hot
Solution Approach 1:
The patent divides the refrigerant flow into two independent streams using a flow control valve, allowing separate control of the cooling capacity (through the indoor heat exchanger) and heating capacity (through the reheater). This segmentation enables precise adjustment of the net heating or cooling effect to match the supply air setpoint, solving the temperature control problem while maintaining reasonable system complexity
3Use of energy by moving object
If the compressor operates at low part load to meet mild ambient temperature conditions, then energy efficiency is improved, but the supply air temperature becomes too cold or the reheater air becomes too hot for the space
Solution Approach 1:
The patent implements dynamic control of the flow control valve to adjust the ratio of refrigerant flow between the indoor heat exchanger and reheater based on real-time temperature feedback. This dynamic adjustment allows the system to maintain optimal temperature control even when the compressor operates at low part load, preventing supply air from being too cold or reheater air from being too hot
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 approach enables controlled reheating of overcooled air, improving the comfort level of a space by ensuring the supply air temperature is neither too cold nor too hot, thus addressing the inconsistencies in existing VRF systems.
Implementation Method 1
a compressor compresses a refrigerant
Implementation Method 2
the first heat exchanger removes heat from a first portion of the refrigerant from the compressor
Implementation Method 3
the second heat exchanger uses the first portion of the refrigerant from the first heat exchanger and the second portion of the refrigerant from the reheater to cool air proximate the second heat exchanger
Implementation Method 4
the reheater uses the second portion of the refrigerant from the compressor to heat the air moved by the blower
Data Source
AI summary
An apparatus includes a compressor, a first heat exchanger, a reheater, a first valve, a second heat exchanger, a four-way valve, a cap tube, and a blower. The compressor compresses a refrigerant. The blower moves air proximate the second heat exchanger to the reheater. During a heating mode of operation, the four-way valve is configured to direct refrigerant from the compressor to the second heat exchanger; the second heat exchanger is configured to use the refrigerant from the compressor to heat air proximate the second heat exchanger; and the cap tube is configured to allow refrigerant to bypass the reheater.