The Prospects of Alternatives to Vapor Compression Technology for Space Cooling and Food Refrigeration Applications

TLDR: In this paper, the authors identify and describe five alternative cooling technologies (magnetic, thermionic, thermoacoustic, thermoelectric, and thermotunnel) and qualitatively assesses the prospects of each technology relative to vapor compression for space cooling and food refrigeration applications.

Abstract: This article identifies and describes five alternative cooling technologies (magnetic, thermionic, thermoacoustic, thermoelectric, and thermotunnel) and qualitatively assesses the prospects of each technology relative to vapor compression for space cooling and food refrigeration applications. Assessment of the alternatives was based on the theoretical maximum percent of Carnot efficiency, the current state of development, the best percent of Carnot efficiency currently achieved, developmental barriers, and the extent of development activity. The prospect for each alternative was assigned an overall qualitative rating based on the subjective, composite view of the five characteristics.

Figures

Figure 8. Standing-Wave Heat Pump (a and b) and Heat Engine(c and d) (Garrett and Backhaus 2000)

Figure 3. Magnetic and Vapor Compression Cooling Cycles (Wikipedia)

Figure 11. Temperature Induced Voltage Potential (Yang 2007)

Figure 12. The Seebeck Effect (Tellurex 2010a)

Table 2. Design Conditions for Fluid Refrigerants

Table 3. Design Conditions for Solid Refrigerants

Full text

PNNL-19259
Prepared for the U.S. Department of Energy
under Contract DE-AC05-76RL01830
The Prospects of Alternatives to
Vapor Compression Technology for
Space Cooling and Food
Refrigeration Applications
DR Brown N Fernandez
JA Dirks TB Stout
March 2010

The Prospects of Alternatives to
Vapor Compression Technology for
Space Cooling and Food
Refrigeration Applications
DR Brown N Fernandez
JA Dirks TB Stout
March 2010
Prepared for
the U.S. Department of Energy
under Contract DE-AC05-76RL01830
Pacific Northwest National Laboratory
Richland, Washington 99352

iii
Summary
Five alternatives to vapor compression technology were qualitatively evaluated to determine their
prospects for being better than vapor compression for space cooling and food refrigeration applications.
The results of the assessment are summarized in Table 1. Overall, thermoacoustic and magnetic
technologies were judged to have the best prospects for competing with vapor compression technology,
with thermotunneling, thermoelectric, and thermionic technologies trailing behind, in that order.
Thermoacoustic and magnetic technologies look relatively attractive because many working prototypes
have already been built, the development barriers appear moderate, and the potential efficiencies are
medium to high. Thermotunneling has a high efficiency potential, but the difficulty of creating and
maintaining the nanometer scale gaps required by the technology significantly lowered its rating. The
recent development of better materials opens the door for improvements in the performance of
thermoelectric coolers, but not enough to be competitive with vapor compression coolers. Thermionic
devices have the capability for very high cooling densities, which will likely lead to microelectronic
applications, but its inherently low efficiency makes it a very poor prospect for eventually competing
with vapor compression technology.
Four of the five alternative technologies (all but thermoacoustic) use solid “refrigerants,” which allows
direct contact heat transfer at the “evaporator” and “condenser.” This effectively cuts the approach
temperature by about 50% compared to vapor compression technology because the refrigerant-side
resistance to heat transfer is eliminated. The performance impact is a 10-20% increase in coefficient of
performance (COP), depending on the rating conditions for cooling source and sink temperature.
Table 1. Prospects of Alternatives to Vapor Compression Technology
Technology Theoretical
Maximum
Carnot
Efficiency
State of
Development
Best Carnot
Efficiency
Achieved
Development
Barriers
Extent of R&D
Activity
Prospect for
Competing
with Vapor
Compression
Thermoelectric 25-35% Commercial 10-15% Medium Many players Fair
Thermionic 20-30% Experimental < 10% High A few players Poor
Thermo-
tunneling
50-80% Experimental No data Very High A few players Average
Thermoacoustic 60-100% Prototype ≈ 20% Medium Many players Good
Magnetic 50-60% Prototype ≈ 20%
1
Medium Many players Good
Vapor
Compression
70-80% Commercial 60% Already
developed
Widespread
1
Higher Carnot efficiencies have been reported, but these were for relatively low temperature spans.

Frequently asked questions

Q1. What are the contributions mentioned in the paper "The prospects of alternatives to vapor compression technology for space cooling and food refrigeration applications" ?

In this paper, the authors identify and describe alternatives to vapor compression cooling technology and qualitatively assesses the relative prospects of the alternatives for space cooling and food refrigeration applications. 

Q2. What are the advantages of vapor compression technology?

Thermionic devices have the capability for very high cooling densities, which will likely lead to microelectronic applications, but its inherently low efficiency makes it a very poor prospect for eventually competing with vapor compression technology. 

Q3. What is the rating of the vapor compression technology?

Thermotunneling has a high efficiency potential, but the difficulty of creating and maintaining the nanometer scale gaps required by the technology significantly lowered its rating.