WSU Energy Program Logo
Bonneville Power Administration Logo
  • Home
  • About
  • Database
      • Browse
      • Energy Systems
        • Building Envelope
        • Electronics
        • HVAC
        • Irrigation
        • Lighting
        • Motors & Drives
        • Multiple Energy Systems
        • Power Systems
        • Process Loads & Appliances
        • Refrigeration
        • Transportation
        • Water Heating
      • Sector
        • Agricultural
        • Commercial
        • Industrial
        • Residential
        • Utility
  • TAG Portal
      • 2017 Residential Lighting TAG (#14)
      • 2016 Multifamily Building TAG (#13)
      • 2015-1 Commercial HVAC TAG (#11)
      • 2014 Residential Building TAG (#10)
      • 2014 Commercial Building TAG (#9)
      • 2013 Information Technology TAG (#8)
      • 2013 ALCS TAG (#7)
      • 2012 Smart Thermostat TAG (#6)
      • 2012 LED Lighting TAG (#5)
      • 2011 Energy Management TAG (#4)
      • 2010 HVAC TAG (#3)
      • 2009 HVAC TAG (#2)
      • 2009 Lighting TAG (#1)
  • Webinars
    • Webinar Archives
  • Glossary
>

Summary

Industrial Heat Pumps

Low-grade waste heat: Boost with Heat Pump vs. Exhaust

Heat pumps that increase the temperature of a low-grade waste heat stream that may otherwise be exhausted to the environment, to make it more useful for industry—for direct process use or to preheat supply or combustion air.

Synopsis:

Industrial heat pumps convert low-grade waste heat that would otherwise be rejected into the environment into high grade thermal energy that is useful to industry.  To boost the temperature of the low grade heat, mechanical heat pumps require shaft horsepower and consume electrical energy.   

The coefficient of performance (COP) of a heat pump is equal to the useful energy output divided by the energy input. COP decreases as the temperature lift (difference between the evaporator and condenser temperatures) increases. 

Continuous flow dehumidification heat pump dryers dehumidify process air with the evaporator coils of a refrigeration system, and then reheat supply air at the condenser coils. They save energy by continuously recycling heat and air within the dryer rather than discharging it to atmosphere.  These units generally have a COP between 5 and 7 when used at low and moderate temperatures and are ideal for drying of lumber and food products.  Energy requirements approach 300 Btu per pound of water vapor removed, about 1/10th of the energy required in conventional dryers.  Designs must ensure that heat transfer surfaces are easily cleaned, to prevent fouling.

Heat pumps are useful when they can deliver heat at a lower cost than the next best alternative.  Alternatives are usually natural gas, propane or other fuel-fired equipment such as steam systems or burners in an oven or dryer.  Mechanical heat pumps use electrical energy while savings natural gas, biomass, or other fuels.

Energy Savings: 27%
Energy Savings Rating: Extensive Assessment  What's this?
LevelStatusDescription
1Concept not validatedClaims of energy savings may not be credible due to lack of documentation or validation by unbiased experts.
2Concept validated:An unbiased expert has validated efficiency concepts through technical review and calculations based on engineering principles.
3Limited assessmentAn unbiased expert has measured technology characteristics and factors of energy use through one or more tests in typical applications with a clear baseline.
4Extensive assessmentAdditional testing in relevant applications and environments has increased knowledge of performance across a broad range of products, applications, and system conditions.
5Comprehensive analysisResults of lab and field tests have been used to develop methods for reliable prediction of performance across the range of intended applications.
6Approved measureProtocols for technology application are established and approved.

Status:

Details

Industrial Heat Pumps

Low-grade waste heat: Boost with Heat Pump vs. Exhaust

Heat pumps that increase the temperature of a low-grade waste heat stream that may otherwise be exhausted to the environment, to make it more useful for industry—for direct process use or to preheat supply or combustion air.
Item ID: 457
Sector: Industrial
Energy System: Process Loads & Appliances--Industrial Processes

Synopsis:

Industrial heat pumps convert low-grade waste heat that would otherwise be rejected into the environment into high grade thermal energy that is useful to industry.  To boost the temperature of the low grade heat, mechanical heat pumps require shaft horsepower and consume electrical energy.   

The coefficient of performance (COP) of a heat pump is equal to the useful energy output divided by the energy input. COP decreases as the temperature lift (difference between the evaporator and condenser temperatures) increases. 

Continuous flow dehumidification heat pump dryers dehumidify process air with the evaporator coils of a refrigeration system, and then reheat supply air at the condenser coils. They save energy by continuously recycling heat and air within the dryer rather than discharging it to atmosphere.  These units generally have a COP between 5 and 7 when used at low and moderate temperatures and are ideal for drying of lumber and food products.  Energy requirements approach 300 Btu per pound of water vapor removed, about 1/10th of the energy required in conventional dryers.  Designs must ensure that heat transfer surfaces are easily cleaned, to prevent fouling.

Heat pumps are useful when they can deliver heat at a lower cost than the next best alternative.  Alternatives are usually natural gas, propane or other fuel-fired equipment such as steam systems or burners in an oven or dryer.  Mechanical heat pumps use electrical energy while savings natural gas, biomass, or other fuels.

Baseline Example:

Baseline Description: Dryer with Dehumidification Heat Pump
Baseline Energy Use: 51344272 kWh per year per Dryer

Comments:

This analysis assumes installation of a dehumidification heat pump on an apple dryer that initially consumes 206,163 MMBtu/year of natural gas. Units are converted to electrical energy equivalents given an 85% burner efficiency as some dryers may not use direct fired gas heat due to taste and flavor issues associated with direct combustion product contact. The dehumidification heat pump would recover the heat of vaporization of water vapor in the exhaust stream and preheat the supply air to the dryer to 140 deg F. Annual energy savings (given 350 tons/day processed, 38 weeks/year, 51% run time per day, and moisture content reduction in the product from 80% to 20%) are 13,765,016 kWh/year, equivalent to 26.8% of the baseline energy use.

Manufacturer's Energy Savings Claims: Currently no data available.
Best Estimate of Energy Savings:

"Typical" Savings: 27%
Energy Savings Reliability: 4 - Extensive Assessment

Comments:

Energy Use of Emerging Technology:
37,481,318.6 kWh per Dryer per year What's this?

Energy Use of an Emerging Technology is based upon the following algorithm.

Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))

Technical Potential:
Units: Dryer
Currently no data available.
First Cost: Currently no data available.

Cost Effectiveness:

Simple payback, new construction (years): N/A

Simple payback, retrofit (years): N/A

What's this?

Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.

Reference and Citations:

WSU EEP, 06/11/2009. Industrial Heat Pumps for Low-Temperature Heat Recovery
Washington State University Extension Energy Program, Industrial Services

IEA/OECD, 01/01/2013. Heat Pumps in Industry
IEA/OECD Heat Pump Centre

Cecilia Arzbaecher, 06/21/2007. Industrial Waste-Heat Recovery: Benefits and Recent Advancements in Technology and Applications
European Council for an Energy Efficiency Economy

EERE, 07/15/2003. Industrial Heat Pumps for Steam and Fuel Savings
Industrial Technologies Program

Rank & Scores

Industrial Heat Pumps

There is no TAG available for this technology.
Contact
Copyright 2023 Washington State University
disclaimer and privacy policies

Bonneville Power Administration Logo