International Communications in Heat and Mass Transfer 39 (2012) 1467–1473

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International Communications in Heat and Mass Transfer

j ourna l homepage: www.e lsev ie r .com/ locate / ichmt

Socioeconomic impacts of heat transfer research☆

Robert A. Taylor a,⁎, Patrick E. Phelan b, Todd Otanicar c, Ravi S. Prasher d, Bernadette E. Phelan e

a University of New South Wales, Sydney, NSW, Australiab Arizona State University, Tempe, AZ, USAc The University of Tulsa, Tulsa, OK, USAd US Department of Energy, Washington DC, USAe Phelan Research Solutions, Inc., Scottsdale, AZ, USA

☆ Communicated by W.J. Minkowycz.⁎ Corresponding author.

E-mail address: Robert.Taylor@UNSW.edu.au (R.A. T

0735-1933/$ – see front matter © 2012 Elsevier Ltd. Allhttp://dx.doi.org/10.1016/j.icheatmasstransfer.2012.09.0

a b s t r a c t

a r t i c l e i n f o

Available online 20 September 2012

Keywords:ResearchImpactsEconomyPatentsPublishing

Heat transfer research affects almost every sector of the economy, yet its impacts have not been well studied orcommunicated to date. To address this issue, this article evaluates recent heat transfer research trends andwhichparts of the economy are likely to be affected by it. Analysis is done through keywords in heat transfer journals,US NSF awards, US patents, and trends in US economic sectors. This study indicates that if heat transfer researchhelps to attain a 10% conversion efficiency gain in all relevant sectors of the US economy, ~110 billion dolars ofannual value added could be generated.

© 2012 Elsevier Ltd. All rights reserved.

1. Introduction

What is the impact of heat transfer research? Additionally, whattype of heat transfer research should be pursued? There is a growingbody of evidence which partially answers these questions for re-search in general [1–7], but very little has been published specificallyfor heat transfer research. Discussion of the questions above is imper-ative because it provides a potential avenue for researchers to engagethe broader technical and non-technical community. This is not welldone in the thermal sciences at present. While developments in cho-lesterol or pain medication and advancements in refrigeration tech-nology are both significant to society, pharmaceutical researchresults are disseminated much more broadly. To help address theseissues, we will briefly review the case for research in general,followed by an examination of the field of heat transfer researchtoday and how it contributes to the US economy. This analysis willrely on key measureable inputs and outputs of heat transfer research.Our objective here is not to draw firm conclusions about where orhow much research funding should be allocated, but rather to con-tribute to a dialogue about the role of heat transfer research in societyat large. We propose that by discussing the impacts of their work,researchers can better communicate what is to be gained frominvesting resources in heat transfer research.

To give one anecdotal example, a number of ‘non-heat transfer’ ac-ademic colleagues at one of the co-author's institutions were largelyunaware of the connection between heat transfer and energyresearch. This implies that either: a) heat transfer research is not

aylor).

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making contributions to global energy challenges, OR, b) the link betweenheat transfer research and energy issues is not being discussed — evenwith other members of academia. We suggest the latter implication ismore likely since heat transfer processes are integral to almost all energysystems, including: heating/cooling of buildings, automobiles, and powerplants.

University researchers are largely free to investigate any avenuethey prefer, but many times research is steered towards potentialfunding opportunities. This indicates that funding agencies – public(e.g. the US National Science Foundation or the Australian ResearchCouncil) and private (e.g. charitable organizations or corporate R&Dprograms) – essentially determine what research gets done. Attimes, special programs are formed to address particular issues or tofulfill the mission of the particular agency (e.g. ARPA-E's HEATS pro-gram or the Australian Solar Institute's United States-Australia SolarEnergy (USASEC) Collaboration). On such occasions, research impactscan be quantified by howwell the program objectiveswere addressed.While many of these types of programs are available, they representonly one part of the funding available for heat transfer research. Re-gardless of the drivers for research, it is important to determinewhat society gets from research — i.e. what is its value? Answeringthis question – and communicating those answers – is essentialbecause up to 60% 1 of US heat transfer research funding comes fromfederal sources (i.e. taxpayers) [8].

We suggest that even in the absence of formal, well-defined pro-grams, heat transfer research is fundamentally focused on solvingproblems that are important to society. One potential way to improve

1 Based on the 200–2010 funding proportion for Engineering research— this propor-tion is in decline [8].

2 “Refriger” is used to capture “refrigerant,” “refrigeration,” “refrigerate,” etc.

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communication is to discuss the historical impacts of heat transfer re-search. Additionally, if we want heat transfer research to have a sub-stantial impact, it is logical to focus efforts on sectors/areas which canprovide the biggest socioeconomic return on research investment.That said, how can decisions potentially be made as to what sectorsof the economy and what challenges are worthy of funding re-sources? The following sections should shed some light on this ques-tion and the others posed above.

2. General impact of research

In this section we provide a brief background of the general im-pacts of research which also, presumably, hold true for heat transferresearch. It is a general notion that research benefits a nation's eco-nomic competitiveness. In 2004, King presented a comprehensiveanalysis of research output as measured by publications, citations,and the top 1% highly cited publications [3]. This was comparedwith a nation's economic strength [3]. In general a positive correla-tion exists between citation intensity (citations/GDP, where GDP =Gross Domestic Product) and wealth intensity (GDP per capita).However, above ~$25,000 in GDP per capita there is considerablescatter. Smaller European nations like Switzerland, Sweden, andIsrael have a higher citation intensity than the US and Japan. Itis also clear from this article that research is heavily concentrat-ed in a relatively few countries.

Salter et al. focused on the benefits of publically funded research,and noted that the rate of return on publically funded academic re-search was 20 to 40%, although this may be declining [4]. Theynoted that publically funded research benefits companies in differentways, i.e., pharmaceutical companies see direct benefits, while auto-motive companies derive benefits largely by the training providedby academic research. There is also an important geographical dimen-sion, in that firms located near research centers derive greater benefitthan those further away. Also, academic research seems to encourageindustrial research, but not vice versa.

With regard to the direct economic impact of research, Nemet andKammen [6] and Toole [1] point to the connection between the num-ber of patents generated in a particular field [6], or the products gen-erated by the pharmaceutical industry [1] [4], and the amount ofresearch and development funding. Given that Nemet and Kammen[6] specifically address the field of energy, this is highly relevant forheat transfer research. Overall, benefits of research (privately andpublically funded) are well enunciated by Martin [9]:

• Increasing the stock of useful knowledge• Training skilled graduates• Creating new scientific instrumentation and methodologies• Forming networks and stimulating social interaction• Increasing the capacity for scientific and technological problem-solving

• Creating new firms

An investigation comparable to Refs. [3–6] on the impact of heattransfer research has not, to our knowledge, been presented. This ar-ticle will provide the requisite background and point out the most im-portant areas for future comprehensive investigations in heat transferresearch.

3. The field of heat transfer research today

What is the current direction of the majority of heat transfer re-search? We propose the following three measures should yield a“snapshot” of current research efforts: a search for keywords in the ti-tles and abstracts of papers published in heat transfer journals,awards granted by the Thermal Transport Processes Program of theUS National Science Foundation (NSF), and patent filings.

3.1. Heat transfer publication analysis

To obtain a snapshot of the research being published, we analyze‘salient’ keywords in the following five heat transfer journals: AppliedThermal Engineering (ATE), International Communications in Heat andMass Transfer (ICHMT), Journal of Heat Transfer (JHT), InternationalJournal of Thermal Sciences (IJTS), and International Journal of Heatand Mass Transfer (IJHMT). Approximately 7500 research articleswere published in these journals during the five full years, 2007–2011.While this represents only 10–20% of the available, relevant literature,it does provide a substantial purposive subset of academic heat transferliterature during this time frame. A list of ‘salient’ keywords for analysiswas chosen by examining the actual keywords for every article inIJHMT between 2007 and 2011. In IJHMT during this period, commonkeywords are ‘heat’, ‘transfer’, ‘flow’, ‘thermal’, ‘method’, and ‘mass’ —which appear approximately1400, 900, 700, 370, 330, 300, and 150times, respectively. It should be noted that the words ‘heat’, ‘transfer’,and ‘mass’ are redundant for authors to use as official keywords sincethose already appear in the journal name. While these commonly usedkeywordsmight be informative in patenting, they do little to distinguishthemselves amongst heat transfer research articles. As such, we analyzeonly themost commonly occurring ‘salient‘ keywords from this list— i.e.those which specify the type of heat transfer research accomplished inthe article. Fig. 1 presents a howoften these keywords appear in the titlesof these journals during over five full years (2007–2011). The compositebars indicate how this research is distributes between journals. Some-what surprisingly, the word “porous” is found to be the most prevalent‘salient’ word in the abstracts of these journals, but more than halfof them come from one journal (IJHMT). The next most frequentlyused word in abstracts is “cooling,” followed in turn by “heatexchanger,” “microchannel,” “nanofluid,” “refriger,”2 “engine,” andso forth. Other words that appear are “solar,” “electronic,” and“nanoparticle,” indicating the continuing or recent emphasis onthese fields. Fig. 2 shows trends in the occurrence of the most pop-ular of these words over the five year period. Many of these wordsshow an increase in frequency over time. The most noticeable in-crease over time is found in the word ‘nanofluid’ — which goesfrom occurring in 17 article abstracts in 2007 to 99 in 2011.

3.2. Heat transfer funding analysis

In a similar manner, Fig. 3 presents a keyword count for recentNSF awards (2006–2011). It is interesting that “engine” is the mostcited word, since it is not used as frequently in journal publications.It should be noted that the frequency of ‘engine’ drops off consider-ably for NSF awards in 2010 and 2011 from its peak in 2008. Follow-ing “engine,” other highly cited words are “nanoscale,” “electronic,”“nanoparticle,” “interface,” “thermal conductivity,” and “cooling.”Figs. 1–3 also show that while “porous” is frequently found in journalkeywords, it is well down the list in terms of NSF-supported awards.There is clearly some correlation between the words found in re-search grants and those that appear in publications (e.g., “engines”and “cooling”), but the correlation is not perfect. One simple expla-nation for this is that ‘developing the knowledge base’ (i.e. publish-ing research articles) is just one of the criteria for deciding whichresearch deserves funding. If this were indeed the only criterion, re-search would likely have a low return on investment.

3.3. Heat transfer patents

A third key measure of the impact of heat transfer research is theinvention of new products, technology, and improved designs. A goodestimate of the impact in this area can be determined from the

Fig. 1. Prevalence of article titles appearing in 5 heat transfer journals from 2007 to 2011 containing the ‘salient’ keywords (Journals: ATE-Applied Thermal Engineering,ICHMT-International Communications in Heat and Mass Transfer, JHT-Journal of Heat Transfer, IJOTS-International Journal of Thermal Sciences, IJHMT-International Journal of Heatand Mass Transfer).

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number of patents filed. The US Patent Office provides a good subsetof this activity since the United States patent historically grants alarge fraction of the world's patents — although Japan's patent officehas issued more several times since 1995 [10]. Fig. 4 shows the prev-alence of heat transfer keywords from above as they appear in patentabstracts according to a keyword search of the USPTO full text andimage data base, which lists patents from 1976 onwards [11]. Toput this in perspective, since 1976 there have been about 4.66 milliontotal patents issued and the word ‘heat’ appears in about 3.4% of theabstracts, while ‘engine’ and thermal have appeared in 2.2% and1.6% of the abstracts, respectively [11]. It should be noted that manyof the heat transfer words are much more prevalent than ‘pharma-ceutical’ or ‘medical’ which appear in 0.8% and 0.6% of all US patentabstracts, respectively. Fig. 5 shows the frequency of occurrence ofthe top four heat transfer words in abstracts since 1976 (given in

Fig. 2. Prevalence of heat transfer article titles containing the most

5 year spans). For each of these words, the five year period fromJanuary 2000 to December 2004 represented the peak in occurrence.It should also be noted that total US patents followed a similar arcwith a peak between 2000 and 2004, presumably due to US economicconditions in recent years.

3.4. Economics and heat transfer

In this section, we will estimate the economic impact of heattransfer research. To do so, we limit ourselves to the US economy,and in particular focus on how different sectors contribute to theGDP — the traditional measure of a nation's economic strength. It isfirst instructive to examine the relative contributions of all major sec-tors to the US GDP, as measured by the US Bureau of Economic Analysis(BEA) [12]. Fig. 6 shows how major sectors have contributed to the

prominent ‘salient’ keywords in the recent years 2007–2011.

Fig. 3. Yearly variation in the prevalence of NSF-awarded grant abstracts containing the keywords (Engineering Directorate, Chemical, Bioengineering, Environmental and TransportSystems (CBET) Division, Thermal Transport Processes Program).

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GDP from 1998 to 2010. These data are given in terms of value added,that is, the output of each sector minus the inputs to that sector. Thesectors with the greatest contribution are “finance, insurance, real es-tate, rental, and leasing,” but of course heat transfer does not playmuch of a role in these sectors. Nonetheless, Fig. 6 gives a goodsense of relative weight of each sector. Manufacturing is the largestsector where heat transfer plays some role, but this role is only aminor one. Fig. 6 also shows that in contrast to the long-termtrend there is a small uptick from 2009 to 2010 in the manufactur-ing sector.

In what sectors can heat transfer be considered to play a majorrole? Based upon the categorization provided by the BEA, and delvingdeeper into its subcategories (that is, not limiting ourselves to just themajor categories shown in Fig. 5), we consider the following sectorsto have significant roles for heat transfer:

• Utilities• Chemical products

Fig. 4. Prevalence of abstracts containing the keyword for US

• Computer and electronic products• Petroleum and coal products• Truck transportation• Paper products• Air transportation• Primary metals

Naturally, other lists could be formed, but we consider only cate-gories given by the BEA which, in our judgment, include a significantheat transfer component. The value added as percent of GDP for theseparticular categories are given in Fig. 6. The “utilities” sector is nearthe top of this graph, ranging between 1.6% and 1.8% of GDP. This in-dicates that energy conversion, from a fuel to electric power, is asignificant part of the US economy. “Chemical products” is next in im-portance, followed by “computer and electronic components” whichin fact ties “chemical products” in 2008 and 2009. The “petroleumand coal products” sector shows the largest variations, due presum-ably to the large fluctuations in the price of petroleum during this

PO abstract filings (total over the years of 1976–2012).

Fig. 5. Historical trends of the top 4 keywords in USPO abstract filings. Note: Bars representfive year groupings during the period 1976–2010.

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time period. Additionally, these sectors may have multiple supplychain steps where heat transfer is important.

The “utilities” sector is definitely important for the US economy,and is indeed a sector where heat transfer plays a critical role,through the combustion of coal or natural gas and in boilers and con-densers of steam power plants. These are areas in which heat transfercontributes to the supply of electricity, but the end uses of electricityand heat might be even more important. Buildings (residential andcommercial) consume approximately one third of US energy. Fig. 8shows building energy end-use expenditures, for both 2008 and2010, as given in the respective Buildings Energy Data Book providedby the US Department of Energy [12]. Note that the values in Fig. 8are in 2009 $ billion for both the 2008 and the 2010 data. Thesedata are for the entire building stock in the USA — residential andcommercial. They consider not only electricity consumption, butalso natural gas and other sources, such as fuel oil. “Space heating”is the largest cost, followed by “lighting,” “space cooling,” “waterheating,” and “refrigeration.”

Taken together these eight sectors represent a modest total contri-bution to the US economy — about seven percent of the total GDP. If

Fig. 6. Value added as a percentage of USA Gross Domestic Product (GPA), fo

heat transfer can make a significant improvement in these areas, itwill mean a big impact on the whole economy. In the next sectionwe will attempt estimate this impact.

3.5. Potential value added and/or savings

Calculations based on data from the EIA's Annual Energy Reviewindicate that, on average, US power plants had the following averageconversion efficiencies in 2010: coal, 33.15%, natural gas, 44.15%, andnuclear, 32.46% [13]. In 2010 these three sources made up 89.0% ofthe total electrical generation market which was calculated at US$340.2 billion. This estimate was calculated by assuming 9.88 centsper kWh, including taxes which is the average retail price for electric-ity in 2010 according to the EIA [13]. Heat transfer research couldeventually bring up the efficiency significantly in this sector, becausethese are nowhere near the Carnot efficiency limit. It is possible thatheat transfer research could bring this efficiency up by 15–30% inthe case of coal and nuclear power, and by 10–20% for natural gaselectrical generation. These increases are achievable by updatingaging power plants with new plants that operate at higher tempera-ture and with those that use advanced cycles. If realized, this wouldrepresent a huge savings to the economy as the same amount of elec-tricity could be generated with much less primary energy consump-tion. If we assume new technology to have roughly the same capitalcost as conventional technology and that approximately 30% of theretail price is incurred from fuel costs, an annual savings of US$45 billion may be possible in the retail electric market through re-search and innovation. Alternatively, if current power plants can beretrofitted to achieve this order of efficiency improvement the UnitedStates could generate 480 billion kWh extra per year. This is enoughto meet the EIA projected demand increases through 2030 [13].

In economic sectors where heat transfer plays a significant role,whether in the supply of electricity or in reducing building end-useconsumption, there is the potential for a direct economic benefit tobe realized. It is beyond the scope of this paper to ascertain preciselythe heat transfer contribution for a given sector, and its correspond-ing economic impact. Instead, we give only a rough estimate of thepotential economic contribution of heat transfer research and innova-tion. We do this by assuming that improved heat transfer – stemmingfrom heat transfer research – leads to a 10% increase in the value

r all major categories as defined by the US Bureau of Economic Analysis.

Fig. 7. Potential improvement curve for energy conversion in the utilities (electric) sector.

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added by a given sector. While this is a rough estimate, we believe thatit does present a feasible potential goal for the long-term economic con-tribution of heat transfer research. Fig. 9 presents graphically the eco-nomic magnitude (in value-added 2010 US $ billion) of the mostimportant sectors identified in Fig. 7 (“petroleum and coal products,”“computer and electronic products,” “chemical products,” and “utili-ties”) and Fig. 8 (“refrigeration,” “water heating,” “space cooling,” and“space heating”), given in ascending order. For purposes of comparison,the end-use expenditures of Fig. 7 are considered to be “value-added.” Itshould also be noted that a 10% improvement at end-use is worthmuchmore than that same improvement upstream.

What does Fig. 9 tell us? If one accepts that heat transfer can oneday lead to a 10% improvement across the sectors where heat transferis important, a $110 billion economic impact is possible per year.Even in the smallest sector in Fig. 9, “refrigeration,” the potential eco-nomic impact is $2.6 billion. Fig. 9 is somewhat consistent with thekeywords from the NSF's awards in Fig. 2, namely, “engine” and “elec-tronic,” suggesting that the NSF funding priorities are at least partiallyaligned with the nation's economic priorities. Fig. 9 might also beinterpreted as a supporting argument for funding heat transfer re-search in fields of energy which provide the largest potential paybackon investment — (i.e., the “utilities” sector), “chemical products,”

Fig. 8. Distribution of building end

“computer and electronic products,” and so forth, with the economic jus-tification increasing as one proceeds from left to right.

4. Conclusions

The impact of heat transfer research has not been well quantifiedor communicated to date. A “snapshot” of recent publications in heattransfer journals, US patenting trends, and awards made by the USNational Science Foundation's Thermal Transport Processes Pro-grams, reveals the trajectory for heat transfer research. These findingsare compared to sectors in the US economy that contribute to theGross Domestic Product (GDP). From an economic point of view, themost important sectors for heat transfer research appear to be utili-ties (that is, energy conversion, energy efficiency, etc.), chemicalproducts, computer and electronic products, and petroleum and coalproducts. Among building energy end uses, heat transfer researchcan have the greatest economic impact in space heating, spacecooling, water heating, and refrigeration. Heat transfer research andtraining in the electrical utilities sector alone is estimated to poten-tially generate roughly $45 billion in savings for the United States oran additional 480 billion kWh supplied given today's generationcapacity. If we could distribute heat transfer improvements across

-use expenditures in the USA.

Fig. 9. Expected value added (10%) by heat transfer research in 2010 ($ billions).

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all sectors, it would be possible to generate economic ‘value added’ onthe order of $110 billion annually.

Supplementary data to this article can be found online at http://dx.doi.org/10.1016/j.icheatmasstransfer.2012.09.007.

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