Blow through direct fired heating, A/C and ERV
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Solution Overview
Problem
Direct fired blow-through heaters combining with direct expansion cooling systems pose risks of forming harmful combustion products like phosgene gas due to refrigerant combustion near the flame, and can generate excessive pressures in evaporator coils when heated air passes through, requiring robust and costly coil designs.
Innovation Solution
Incorporating an air switching box and safety circuit to ensure that air does not pass through the evaporator coil during heating mode, and positioning the evaporator coil either upstream or downstream of the burner to prevent refrigerant exposure to the flame, while using energy recovery ventilation to enhance efficiency and indoor air quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the evaporator coil is positioned in the air flow path during heating mode, then cooling function is integrated, but harmful combustion products like phosgene gas form due to refrigerant combustion near the flame
Solution Approach 1:
The system dynamically switches the position of the evaporator coil relative to the air flow path based on operating mode. During cooling mode, the coil is positioned in the air flow path to provide cooling. During heating mode, the coil is repositioned out of the air flow path to prevent refrigerant combustion and formation of harmful combustion products like phosgene gas.
2Use of energy by moving object
If heated air passes through the evaporator coil, then cooling capacity is utilized, but excessive pressures are generated in the coil requiring robust and costly designs
Solution Approach 1:
The evaporator coil's position in the air flow path is dynamically adjusted based on system mode. In cooling mode, the coil receives cooled air flow to provide cooling capacity. In heating mode, the coil is repositioned so that heated air bypasses it, avoiding excessive pressure buildup while maintaining the ability to utilize cooling capacity when needed.
3Ease of manufacture
If a single compact HVAC system integrates heating, cooling, and ventilation, then installation costs are reduced, but system complexity increases requiring air switching boxes and safety circuits
Solution Approach 1:
The patent combines heating, cooling, and ventilation functions into a single compact HVAC system, integrating multiple subsystems to share common components like the blower and evaporator coil. This merging reduces installation costs and space requirements while maintaining individual functionality of each subsystem through controlled operation modes.
Solution Approach 2:
An air switching box is introduced as an intermediary component to manage and switch air flow paths between different functions (heating, cooling, ventilation). This mediator component simplifies the control of complex air flow routing and enables safe operation by preventing heated air from passing through the evaporator coil during heating mode.
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
Prevents the formation of harmful combustion products and excessive pressures, allowing for efficient and safe operation with reduced installation costs by integrating blow-through direct fired heating, direct expansion cooling, and energy recovery ventilation in a single compact HVAC system, improving energy efficiency and indoor air quality.
Implementation Method 1
combining the evaporator coil of an air conditioning system with the air flow of a direct fired system
Implementation Method 2
a direct fired system
Implementation Method 3
energy recovery ventilation to enhance efficiency and indoor air quality
Data Source
AI summary
According to various aspects, exemplary embodiments are disclosed of blow through direct fired heaters including evaporator coils and/or energy recovery ventilation.