Apparatus and method for cleaning HVAC cooling coils
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Solution Overview
Problem
Conventional HVAC cooling coil cleaning methods are inadequate for removing contamination buildup between closely spaced fins, leading to reduced system efficiency, increased energy consumption, and potential health risks from microbiological growth, as they fail to reach deep into thick coils and do not effectively address biofilm formation.
Innovation Solution
A novel apparatus and method utilizing a high-velocity flow of cleaning solution augmented with air to reach deeper into HVAC cooling coils, featuring a supply and collection assembly with a pump, vacuum source, nozzle device, and filter assembly to efficiently remove contaminants and prevent microbial growth, while using a drain basin for solution collection and recirculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional low-pressure sprayer cleaning is used, then the cleaning process is simple and easy to operate, but the cleaning solution cannot reach deep into thick coils with closely spaced fins
Solution Approach 1:
The patent employs high-pressure hydraulic injection to force cleaning solution deep into the coil structure. The system uses a pump to generate high pressure (typically 100-500 psi) that propels cleaning solution through the tightly spaced fins, achieving penetration depths of 6 inches or more into thick coils, whereas conventional low-pressure sprayers only reach a few inches.
2Productivity
If high-velocity cleaning solution flow is used to reach deep into coils, then contamination removal effectiveness is improved, but the complexity of the cleaning apparatus increases
Solution Approach 1:
The system uses a motor-driven pump to generate high-velocity cleaning solution flow, achieving velocities sufficient to penetrate deep into thick coils and remove entrenched contamination. The hydraulic system includes pressure-regulated valves and flow control mechanisms to optimize cleaning effectiveness while managing system complexity.
Solution Approach 2:
The patent introduces air as an intermediary carrier gas that mixes with the cleaning solution to create a two-phase flow. This air-solution mixture enhances penetration into the coil structure and improves the removal of loose contaminants and biofilm, while the air also helps dry the coils more rapidly after cleaning.
3Reliability
If cleaning solution is applied to remove contaminants, then heat transfer efficiency is restored, but cleaning chemicals and contaminants remain trapped in the coil
Solution Approach 1:
The system uses high-velocity reverse flow injection to flush contaminants and cleaning chemicals out of the coil. The cleaning solution is injected at high pressure in the opposite direction of normal airflow, forcing trapped contaminants and residual chemicals through the coil and out the other side, ensuring thorough removal rather than just displacement within the coil.
Solution Approach 2:
The cleaning process employs periodic alternation between forward flow (applying cleaning solution) and reverse flow (flushing out contaminants). This periodic reversal ensures that contaminants and residual chemicals are systematically removed from all sections of the coil, preventing re-deposition and ensuring complete cleaning effectiveness.
4Object-affected harmful factors
If coils are cleaned to remove biofilm, then microbiological growth is prevented, but the cleaning process may damage fragile fins
Solution Approach 1:
The system carefully controls cleaning solution parameters including pH (typically 7-11 for aluminum fins), temperature (60-120°F), and chemical concentration to effectively kill and remove biofilm while being compatible with fin materials. The controlled parameters ensure biocidal effectiveness without causing corrosion or structural damage to aluminum, copper, or stainless steel fins.
Solution Approach 2:
The high-velocity flow regime creates a mechanical scouring effect that physically removes biofilm and contaminants from fin surfaces. The kinetic energy of the high-velocity cleaning solution (achieved through pressurized injection) provides sufficient mechanical force to strip biofilm without requiring harsh chemicals or excessive pressure that could damage the fins.
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
The solution effectively removes contaminants and biofilm from HVAC cooling coils, enhancing system efficiency, reducing energy consumption, and preventing the introduction of harmful microorganisms into the building environment by ensuring thorough cleaning without damaging the coils.
Implementation Method 1
A vacuum source has a vacuum inlet positioned to be in fluid communication with an ullage space such that the vacuum source creates negative pressure in the ullage space during operation
Implementation Method 2
A pump is also provided, having a pump inlet positioned to be in fluid communication with the cleaning solution. The pump is operative to deliver the cleaning solution to a supply outlet of the supply and collection assembly
Data Source
AI summary
A method of cleaning an HVAC coil unit located above a drain basin. One step of the method involves providing a supply and collection assembly having a reservoir containing liquid cleaning solution, a pump operative to output the liquid cleaning solution through a supply outlet, and a vacuum source operative to draw in used liquid cleaning solution through a collection inlet. According to another step, a nozzle device in fluid communication with the supply outlet is also provided, the nozzle device having a delivery face. A further step involves providing a fluid return tool in fluid communication with the collection inlet, and positioning the fluid return tool in the drain basin. According to a further step, the delivery face of the nozzle device is moved across a surface of the HVAC coil unit to deliver the cleaning solution into areas between fins thereof.