Plate Heat Exchanger Warewasher Drain Water Tempering
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Solution Overview
Problem
Commercial warewash machines often discharge drain water at temperatures above plumbing codes due to high temperatures of cleaning and rinse water, requiring additional cold water to temper the drain water, which leads to inefficiencies in energy usage and water management.
Innovation Solution
A waste water heat recovery system utilizing a self-contained plate heat exchanger unit within the warewash machine, where heat from waste water is transferred to fresh water, preheating it for reuse and tempering the waste water to acceptable levels, integrated with a controller for efficient operation and self-cleaning during shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fresh cold water is flushed down the drain with drain water to lower temperature, then drain water temperature is reduced to acceptable levels, but energy efficiency deteriorates due to heating requirements
Solution Approach 1:
The patent converts the harmful hot drain water that needs cooling into a beneficial heat source. The heat exchanger captures thermal energy from the hot drain water and transfers it to the incoming fresh water, transforming the waste heat problem into an energy recovery opportunity that preheats fresh water and reduces overall energy consumption.
Solution Approach 2:
The heat exchanger acts as an intermediary device between the hot drain water and the fresh cold water. It facilitates thermal energy transfer without direct mixing of the two water streams, enabling temperature adjustment of both streams through indirect heat exchange while maintaining system efficiency.
2Use of energy by moving object
If heat recovery systems are implemented to recover heat from drain water, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The heat exchanger unit serves multiple functions simultaneously: it recovers heat from drain water, preheats fresh water for the cleaning cycle, and cools the drain water to meet discharge temperature requirements. This multi-functionality consolidates what would otherwise require separate systems into a single integrated component.
Solution Approach 2:
The system uses the hot drain water itself as the heating source for the fresh water, requiring no external energy input for the heat transfer process. The waste heat automatically serves the dual purpose of cooling discharge water and preheating fresh water, making the system self-sufficient.
3Power
If multiple heat exchanger plates are arranged within the heat exchange volume, then heat transfer efficiency is improved, but device complexity increases
Solution Approach 1:
The heat exchanger is divided into multiple individual plates arranged in series within the heat exchange volume. Each plate provides a separate heat transfer surface, and the cumulative effect of multiple plates significantly increases the total heat transfer area and efficiency compared to a single plate design.
Solution Approach 2:
Multiple heat exchanger plates are nested within a single compact heat exchanger unit housing. The plates are arranged in a space-efficient configuration where each plate fits within the overall unit boundaries, allowing high heat transfer capacity in a compact form factor that integrates easily into the warewashing machine.
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 system effectively recovers energy from waste water, preheats fresh water for reuse, and tempers waste water below acceptable levels, enhancing energy efficiency, reducing water consumption, and providing a self-cleaning mechanism to prevent clogging, while maintaining compliance with plumbing standards.
Implementation Method 1
heat from waste water traveling along the waste water flow path is transferred through the first plate to fresh water traveling along the fresh water flow path
Data Source
AI summary
A warewash machine includes a housing at least in part defining a chamber for cleaning wares and a sump for collecting hot cleaning water that is recirculated through the chamber during cleaning. A drain path is provided for draining cleaning water from the sump and a fresh water input line includes at least a fresh water input that receives fresh water. A waste water heat recovery arrangement includes one or more plate heat exchanger units that transfer heat from the draining cleaning water to the incoming fresh water.