Transport refrigeration system utilizing engine waste heat

Solution Overview

Problem

Conventional transport refrigeration systems for mobile refrigerated cargo increase engine shaft load when operating in heating or defrosting modes, as they require engine power to circulate hot refrigerant vapor or generate electric power for resistance heaters, leading to inefficiencies and increased load on the engine.

Innovation Solution

A transport refrigeration system that utilizes engine waste heat by incorporating an engine coolant circuit with heat exchangers to transfer heat from exhaust gases to coolant and then to the refrigeration unit, allowing for selective heating of cargo box air and defrosting of the evaporator coil without increasing engine load, using a controller to manage the engine coolant distribution and bypassing the refrigeration unit heat exchanger as needed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the refrigeration unit operates in heating or defrosting mode using conventional methods (circulating hot refrigerant vapor or using resistance heaters), then heating and defrosting functions are achieved, but engine shaft load increases

Engineering Contradiction:

Improvecargo box temperatureVSAvoidengine shaft load

Core Design Contradiction:

TemperatureVSPower

Solution Approach 1:

The patent converts the harmful waste heat from engine exhaust into a useful heating source for the cargo box and evaporator defrosting. The exhaust heat exchanger captures thermal energy that would otherwise be wasted, transferring it to the cargo box air or evaporator coil, thereby eliminating the need for additional engine power during heating and defrosting operations.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The engine's own exhaust heat is utilized to serve the heating and defrosting needs of the refrigeration system. The system is self-sufficient by using its own waste products (hot exhaust gases) to meet its thermal requirements, reducing dependence on external engine power for these functions.

Inventive Principle:

Principle #25Self-service

2Temperature

If the refrigeration unit operates in heating mode using hot refrigerant vapor circulation, then cargo box heating is achieved, but engine power consumption increases

Engineering Contradiction:

Improvecargo box temperatureVSAvoidengine power consumption

Core Design Contradiction:

TemperatureVSUse of energy by moving object

Solution Approach 1:

The patent converts the harmful waste heat from engine exhaust into a useful heating source for the cargo box and evaporator defrosting. The exhaust heat exchanger captures thermal energy that would otherwise be wasted, transferring it to the cargo box air or evaporator coil, thereby eliminating the need for additional engine power during heating and defrosting operations.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The engine's own exhaust heat is utilized to serve the heating and defrosting needs of the refrigeration system. The system is self-sufficient by using its own waste products (hot exhaust gases) to meet its thermal requirements, reducing dependence on external engine power for these functions.

Inventive Principle:

Principle #25Self-service

3Loss of energy

If exhaust heat is utilized for heating, then engine efficiency increases and heating capacity is boosted, but exhaust gas temperature decreases

Engineering Contradiction:

Improvewaste heat utilizationVSAvoidexhaust gas temperature

Core Design Contradiction:

Loss of energyVSTemperature

Solution Approach 1:

The patent converts the harmful waste heat from engine exhaust into a useful heating source for the cargo box and evaporator defrosting. The exhaust heat exchanger captures thermal energy that would otherwise be wasted, transferring it to the cargo box air or evaporator coil, thereby eliminating the need for additional engine power during heating and defrosting operations.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The system changes the temperature parameter of the exhaust gases by extracting heat through the exhaust heat exchanger. This parameter change reduces exhaust gas temperature, which enables the safe use of diesel particulate filters that require lower temperatures to function properly.

Inventive Principle:

Principle #35Parameter changes

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 solution reduces engine shaft load by using waste heat for heating and defrosting, increasing overall engine efficiency, boosting heating capacity, and enabling the safe use of diesel particulate filters due to reduced exhaust gas temperatures, while maintaining effective temperature control within the cargo box.

Implementation Method 1

an engine exhaust gases to engine coolant heat exchanger... the engine coolant absorbs heat from the engine exhaust gases and the engine exhaust gases are cooled

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

an engine coolant circuit to refrigeration unit heat exchanger... the flow of box air absorbs heat from the engine coolant

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 3

Air or an air/gas mixture is drawn from the interior volume of the cargo box by means of the evaporator fan(s) associated with the evaporator, passed through the airside of the evaporator in heat exchange relationship with refrigerant whereby the refrigerant absorbs heat from the air

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentUS9789744B2Transport refrigeration system utilizing engine waste heat

Publication Date: 2017.10.17 CARRIER CORP

AI summary

A transport refrigeration system includes a transport refrigeration unit having a refrigerant circuit through which a refrigerant is circulated in heat exchange relationship with air drawn from a cargo box, a fuel-fired engine for powering the refrigeration unit and having an exhaust system through which exhaust gases generated by the engine are discharged and an engine coolant circuit, an engine exhaust gases to engine coolant heat exchanger, and an engine coolant circuit to refrigeration unit heat exchanger.