Advances in Heat Pump-Assisted Drying Technology

Vasile Minea

• Publisher: CRC Press
• Year: 2016
• Print ISBN: 9780367873981
• eBook ISBN: 9781315352671
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Industrial & Technical Chemistry
• Index: Technology & Engineering

Drying of solids is one of the most common, complex, and energy-intensive industrial processes. Conventional dryers offer limited opportunities to increase energy efficiency. Heat pump dryers are more energy and cost effective, as they can recycle drying thermal energy and reduce CO2, particulate, and VOC emissions due to drying. This book provides an introduction to the technology and current best practices and aims to increase the successful industrial implementation of heat pump- assisted dryers. It enables the reader to engage confidently with the technology and provides a wealth of information on theories, current practices, and future directions of the technology. It emphasizes several new design concepts and operating and control strategies, which can be applied to improve the economic and environmental efficiency of the drying process. It answers questions about risks, advantages vs. disadvantages, and impediments and offers solutions to current problems.

Discusses heat pump technology in general and its present and future challenges.

Describes interesting and promising innovations in drying food, agricultural, and wood products with various heat pump technologies.

Treats several technical aspects, from modeling and simulation of drying processes to industrial applications.

Emphasizes new design concepts and operating and control strategies to improve the efficiency of the drying process.

1 Advances in Industrial Heat Pump Technologies and Applications

Vasile Minea

Contents

1.1	Introduction
	1.1.1	World Energy Context
	1.1.2	Classification of Heat Pumps
	1.1.3	Industrial Heat Pumps' Market Outlook
1.2	Subcritical Mechanical Vapor Compression Heat Pumps
	1.2.1	Generalities
		1.2.1.1	Design Outline
		1.2.1.2	Performance Indicators
		1.2.1.3	New Industrial Applications
	1.2.2	Subcritical Mechanical Vapor Compression Heat Pump-Assisted Dryers
		1.2.2.1	Energy Efficiency
		1.2.2.2	Simple Payback Period
		1.2.2.3	Advantages and Limitations
		1.2.2.4	Technological Advances
		1.2.2.5	Industrial Applications of Heat Pump-Assisted Drying
1.3	Supercritical Mechanical Vapor Compression Heat Pumps
	1.3.1	Design Outline
	1.3.2	Performance Indicators
	1.3.3	R&D and Technological Advances
		1.3.3.1	Internal Heat Exchanger
		1.3.3.2	Compression Process
		1.3.3.3	Gas Cooler
		1.3.3.4	Expansion Work Recovery
	1.3.4	Applications of Supercritical CO2 Heat Pumps
		1.3.4.1	Industrial Waste Heat Recovery
		1.3.4.2	Industrial Drying
	1.3.5	Refrigerants
		1.3.5.1	Low-Temperature Synthetic Refrigerants
		1.3.5.2	Natural Refrigerants
		1.3.5.3	High-Temperature Refrigerants
		1.3.5.4	Refrigerant Mixtures
		1.3.5.5	Nanorefrigerants
	1.3.6	Compressors
	1.3.7	Lubricants
	1.3.8	MicroChannel Heat Exchangers
1.4	Ammonia Mechanical Vapor Compression Heat Pumps
	1.4.1	Single-Stage Ammonia Heat Pumps
		1.4.1.1	Residential and Industrial Applications
	1.4.2	Two-Stage Ammonia Heat Pumps
1.5	Absorption Heat Pumps
	1.5.1	Working Fluid Pairs
		1.5.1.1	Ammonia-Water Mixture
		1.5.1.2	Water-Lithium Bromide Mixture
		1.5.1.3	New Working Fluid Pairs
	1.5.2	Single-Stage Ammonia Absorption Heat Pumps
		1.5.2.1	Energy Balance and Thermal Efficiency
	1.5.3	Two-Stage Ammonia Absorption Heat Pumps
	1.5.4	Combined Ejector-Absorption Cycles
	1.5.5	Absorption Heat Transformers
		1.5.5.1	Energy Balance and Thermal Efficiency
	1.5.6	Industrial Applications of Absorption Heat Pumps
	1.5.7	Compression-Absorption (Resorption) Heat Pumps
		1.5.7.1	Single-Phase (Dry) Compression-Absorption Heat Pumps
		1.5.7.2	Double-Phase (Wet) Compression-Resorption (Absorption) Heat Pumps
		1.5.7.3	Industrial Applications of Compression-Absorption Heat Pumps
1.6	Mechanical Vapor Recompression Heat Pumps
	1.6.1	Principle
		1.6.1.1	Compressors
		1.6.1.2	Evaporator-Condenser Heat Exchangers
	1.6.2	Thermal Balances and Energy Efficiency
	1.6.3	Advantages and Limitations
	1.6.4	Industrial Applications
1.7	Chemical Heat Pumps and Transformers
	1.7.1	Chemical Heat Pumps
		1.7.1.1	Principle
		1.7.1.2	Energy Efficiency
	1.7.2	Chemical Heat Transformers
		1.7.2.1	Energy Efficiency
	1.7.3	R&D Advances and Future Needs
	1.7.4	Industrial Applications
		1.7.4.1	Chemical Heat Pump-Assisted Drying
1.8	Solid-State Heat Pumps
	1.8.1	Thermoelectric Heat Pumps
		1.8.1.1	Energy Efficiency
		1.8.1.2	R&D Advances
		1.8.1.3	Applications
	1.8.2	Thermoacoustic Heat Pumps
		1.8.2.1	Principle
		1.8.2.2	Energy Efficiency
		1.8.2.3	Applications and R&D Activities
1.9	Future R&D and Application Challenges
	1.9.1	Residential, Institutional/Commercial Heat Pumps
	1.9.2	Industrial Heat Pumps
		1.9.2.1	Heat Pump-Assisted Drying
References

1.1 Introduction

Depletion of fossil fuels and increasing requirements for the environment protection have prompted academic and industrial R&D communities to develop and promote new, more efficient heating and cooling systems, as heat pumps recovering industrial waste heat (Srikhirin et al. 2001), combined or not with renewable energy sources, such as solar (Nguyen et al. 2001) and/or geothermal energies.

This chapter summarizes recent R&D advancements in heat pump technology and applications, including those reported for industrial drying. The review of R&D advancements refers to new components, such as compressors, working fluids, and heat exchangers, and advanced heat pumping cycles and control methods aiming at enhancing the system's overall energy performances, whereas new industrial applications mainly focus on heat pump integration with various energy sources, such as waste heat and solar energy, and industrial processes such as drying, evaporation, and distillation.

1.1.1 World Energy Context

In 2008, the total world energy supply was 143 851 TWh (corresponding to about 15 TW of energy power), of which oil and coal combined represented over 60% (Figure 1.1a). Industrial users (agriculture, mining, manufacturing, and construction) consumed about 37%, personal and commercial transportation (20%), residential (heating, lighting, and appliances) (11%), and commercial buildings (lighting, heating, and cooling) (5%) of the total world energy supply. The rest, 32%, was lost in energy transmission and generation (IEA 2014) depending on the energy source itself, as well as the efficiency of end-use technologies.

Also in 2008, the world electricity generation was 20 181 TWh, of which more than 60% has been produced by using coal/peat and natural gas as primary energy sources (Figure 1.1b). Refrigeration, heat pump, and air conditioning industries consumed about 10%—15% of this total electric energy production (IEA 2014).

On the other hand, global C0₂ emissions came from electrical power generation (40%), industry (17%), buildings (14%), and transport (21%) energ...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Series Preface
• Preface
• Acknowledgments
• Series Editor
• Editor
• Contributors
• Chapter 1 Advances in Industrial Heat Pump Technologies and Applications
• Chapter 2 Modeling, Simulation, and Optimization of Heat Pump Drying Systems
• Chapter 3 Advances in Heat Pump-Assisted Agro-Food Drying Technologies
• Chapter 4 Advances in Heat Pump-Assisted Drying of Fruits
• Chapter 5 Advances in Heat Pump-Assisted Technologies for Drying of Vegetables
• Chapter 6 Drying of Fruits and Vegetables: The Impact of Different Drying Methods on Product Quality
• Chapter 7 Numerical Modeling of Heat Pump-Assisted Contact Drying
• Chapter 8 Advances in Dehumidifier Timber Drying in New Zealand
• Index