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Socioeconomic impacts of heat transfer research
International Communications in Heat and Mass Transfer 39 (2012) 1467–1473
Contents lists available at SciVerse ScienceDirect
International Communications in Heat and Mass Transfer journal homepage: www.elsevier.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, Australia Arizona State University, Tempe, AZ, USA c The University of Tulsa, Tulsa, OK, USA d US Department of Energy, Washington DC, USA e Phelan Research Solutions, Inc., Scottsdale, AZ, USA b
a r t i c l e
i n f o
Available online 20 September 2012 Keywords: Research Impacts Economy Patents Publishing
a b s t r a c t Heat transfer research affects almost every sector of the economy, yet its impacts have not been well studied or communicated to date. To address this issue, this article evaluates recent heat transfer research trends and which parts 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 research helps to attain a 10% conversion efficiency gain in all relevant sectors of the US economy, ~110 billion dolars of annual value added could be generated. © 2012 Elsevier Ltd. All rights reserved.
1. Introduction What is the impact of heat transfer research? Additionally, what type of heat transfer research should be pursued? There is a growing body of evidence which partially answers these questions for research in general [1–7], but very little has been published specifically for heat transfer research. Discussion of the questions above is imperative because it provides a potential avenue for researchers to engage the broader technical and non-technical community. This is not well done in the thermal sciences at present. While developments in cholesterol or pain medication and advancements in refrigeration technology are both significant to society, pharmaceutical research results are disseminated much more broadly. To help address these issues, we will briefly review the case for research in general, followed by an examination of the field of heat transfer research today and how it contributes to the US economy. This analysis will rely on key measureable inputs and outputs of heat transfer research. Our objective here is not to draw firm conclusions about where or how much research funding should be allocated, but rather to contribute to a dialogue about the role of heat transfer research in society at large. We propose that by discussing the impacts of their work, researchers can better communicate what is to be gained from investing resources in heat transfer research. To give one anecdotal example, a number of ‘non-heat transfer’ academic colleagues at one of the co-author's institutions were largely unaware of the connection between heat transfer and energy research. This implies that either: a) heat transfer research is not ☆ Communicated by W.J. Minkowycz. ⁎ Corresponding author. E-mail address: [email protected] (R.A. Taylor). 0735-1933/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.icheatmasstransfer.2012.09.007
making contributions to global energy challenges, OR, b) the link between heat transfer research and energy issues is not being discussed — even with other members of academia. We suggest the latter implication is more likely since heat transfer processes are integral to almost all energy systems, including: heating/cooling of buildings, automobiles, and power plants. University researchers are largely free to investigate any avenue they prefer, but many times research is steered towards potential funding opportunities. This indicates that funding agencies – public (e.g. the US National Science Foundation or the Australian Research Council) and private (e.g. charitable organizations or corporate R&D programs) – essentially determine what research gets done. At times, special programs are formed to address particular issues or to fulfill the mission of the particular agency (e.g. ARPA-E's HEATS program or the Australian Solar Institute's United States-Australia Solar Energy (USASEC) Collaboration). On such occasions, research impacts can be quantified by how well the program objectives were addressed. While many of these types of programs are available, they represent only one part of the funding available for heat transfer research. Regardless of the drivers for research, it is important to determine what society gets from research — i.e. what is its value? Answering this question – and communicating those answers – is essential because up to 60% 1 of US heat transfer research funding comes from federal sources (i.e. taxpayers) [8]. We suggest that even in the absence of formal, well-defined programs, heat transfer research is fundamentally focused on solving problems that are important to society. One potential way to improve
1 Based on the 200–2010 funding proportion for Engineering research — this proportion is in decline [8].
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communication is to discuss the historical impacts of heat transfer research. Additionally, if we want heat transfer research to have a substantial impact, it is logical to focus efforts on sectors/areas which can provide the biggest socioeconomic return on research investment. That said, how can decisions potentially be made as to what sectors of the economy and what challenges are worthy of funding resources? The following sections should shed some light on this question and the others posed above. 2. General impact of research In this section we provide a brief background of the general impacts of research which also, presumably, hold true for heat transfer research. It is a general notion that research benefits a nation's economic competitiveness. In 2004, King presented a comprehensive analysis of research output as measured by publications, citations, and the top 1% highly cited publications [3]. This was compared with a nation's economic strength [3]. In general a positive correlation 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 considerable scatter. Smaller European nations like Switzerland, Sweden, and Israel have a higher citation intensity than the US and Japan. It is also clear from this article that research is heavily concentrated 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 research was 20 to 40%, although this may be declining [4]. They noted that publically funded research benefits companies in different ways, i.e., pharmaceutical companies see direct benefits, while automotive companies derive benefits largely by the training provided by academic research. There is also an important geographical dimension, in that firms located near research centers derive greater benefit than those further away. Also, academic research seems to encourage industrial research, but not vice versa. With regard to the direct economic impact of research, Nemet and Kammen [6] and Toole [1] point to the connection between the number of patents generated in a particular field [6], or the products generated by the pharmaceutical industry [1] [4], and the amount of research and development funding. Given that Nemet and Kammen [6] specifically address the field of energy, this is highly relevant for heat transfer research. Overall, benefits of research (privately and publically 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 problemsolving • Creating new firms An investigation comparable to Refs. [3–6] on the impact of heat transfer research has not, to our knowledge, been presented. This article will provide the requisite background and point out the most important areas for future comprehensive investigations in heat transfer research.
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: Applied Thermal Engineering (ATE), International Communications in Heat and Mass Transfer (ICHMT), Journal of Heat Transfer (JHT), International Journal of Thermal Sciences (IJTS), and International Journal of Heat and Mass Transfer (IJHMT). Approximately 7500 research articles were 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 transfer literature during this time frame. A list of ‘salient’ keywords for analysis was chosen by examining the actual keywords for every article in IJHMT between 2007 and 2011. In IJHMT during this period, common keywords are ‘heat’, ‘transfer’, ‘flow’, ‘thermal’, ‘method’, and ‘mass’ — which appear approximately1400, 900, 700, 370, 330, 300, and 150 times, respectively. It should be noted that the words ‘heat’, ‘transfer’, and ‘mass’ are redundant for authors to use as official keywords since those already appear in the journal name. While these commonly used keywords might be informative in patenting, they do little to distinguish themselves amongst heat transfer research articles. As such, we analyze only the most commonly occurring ‘salient‘ keywords from this list — i.e. those which specify the type of heat transfer research accomplished in the article. Fig. 1 presents a how often these keywords appear in the titles of these journals during over five full years (2007–2011). The composite bars indicate how this research is distributes between journals. Somewhat surprisingly, the word “porous” is found to be the most prevalent ‘salient’ word in the abstracts of these journals, but more than half of them come from one journal (IJHMT). The next most frequently used word in abstracts is “cooling,” followed in turn by “heat exchanger,” “microchannel,” “nanofluid,” “refriger,” 2 “engine,” and so forth. Other words that appear are “solar,” “electronic,” and “nanoparticle,” indicating the continuing or recent emphasis on these fields. Fig. 2 shows trends in the occurrence of the most popular of these words over the five year period. Many of these words show an increase in frequency over time. The most noticeable increase over time is found in the word ‘nanofluid’ — which goes from 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 recent NSF awards (2006–2011). It is interesting that “engine” is the most cited word, since it is not used as frequently in journal publications. It should be noted that the frequency of ‘engine’ drops off considerably for NSF awards in 2010 and 2011 from its peak in 2008. Following “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 journal keywords, it is well down the list in terms of NSF-supported awards. There is clearly some correlation between the words found in research grants and those that appear in publications (e.g., “engines” and “cooling”), but the correlation is not perfect. One simple explanation for this is that ‘developing the knowledge base’ (i.e. publishing research articles) is just one of the criteria for deciding which research deserves funding. If this were indeed the only criterion, research would likely have a low return on investment.
3. The field of heat transfer research today 3.3. Heat transfer patents What is the current direction of the majority of heat transfer research? We propose the following three measures should yield a “snapshot” of current research efforts: a search for keywords in the titles and abstracts of papers published in heat transfer journals, awards granted by the Thermal Transport Processes Program of the US National Science Foundation (NSF), and patent filings.
A third key measure of the impact of heat transfer research is the invention of new products, technology, and improved designs. A good estimate of the impact in this area can be determined from the 2
“Refriger” is used to capture “refrigerant,” “refrigeration,” “refrigerate,” etc.
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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 Heat and Mass Transfer).
number of patents filed. The US Patent Office provides a good subset of this activity since the United States patent historically grants a large fraction of the world's patents — although Japan's patent office has issued more several times since 1995 [10]. Fig. 4 shows the prevalence of heat transfer keywords from above as they appear in patent abstracts according to a keyword search of the USPTO full text and image data base, which lists patents from 1976 onwards [11]. To put this in perspective, since 1976 there have been about 4.66 million total patents issued and the word ‘heat’ appears in about 3.4% of the abstracts, while ‘engine’ and thermal have appeared in 2.2% and 1.6% of the abstracts, respectively [11]. It should be noted that many of the heat transfer words are much more prevalent than ‘pharmaceutical’ or ‘medical’ which appear in 0.8% and 0.6% of all US patent abstracts, respectively. Fig. 5 shows the frequency of occurrence of the top four heat transfer words in abstracts since 1976 (given in
5 year spans). For each of these words, the five year period from January 2000 to December 2004 represented the peak in occurrence. It should also be noted that total US patents followed a similar arc with a peak between 2000 and 2004, presumably due to US economic conditions in recent years. 3.4. Economics and heat transfer In this section, we will estimate the economic impact of heat transfer research. To do so, we limit ourselves to the US economy, and in particular focus on how different sectors contribute to the GDP — the traditional measure of a nation's economic strength. It is first instructive to examine the relative contributions of all major sectors 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
Fig. 2. Prevalence of heat transfer article titles containing the most prominent ‘salient’ keywords in the recent years 2007–2011.
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Fig. 3. Yearly variation in the prevalence of NSF-awarded grant abstracts containing the keywords (Engineering Directorate, Chemical, Bioengineering, Environmental and Transport Systems (CBET) Division, Thermal Transport Processes Program).
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. The sectors with the greatest contribution are “finance, insurance, real estate, rental, and leasing,” but of course heat transfer does not play much of a role in these sectors. Nonetheless, Fig. 6 gives a good sense of relative weight of each sector. Manufacturing is the largest sector where heat transfer plays some role, but this role is only a minor one. Fig. 6 also shows that in contrast to the long-term trend there is a small uptick from 2009 to 2010 in the manufacturing sector. In what sectors can heat transfer be considered to play a major role? Based upon the categorization provided by the BEA, and delving deeper into its subcategories (that is, not limiting ourselves to just the major categories shown in Fig. 5), we consider the following sectors to have significant roles for heat transfer: • Utilities • Chemical products
• • • • • •
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 categories given by the BEA which, in our judgment, include a significant heat transfer component. The value added as percent of GDP for these particular categories are given in Fig. 6. The “utilities” sector is near the top of this graph, ranging between 1.6% and 1.8% of GDP. This indicates that energy conversion, from a fuel to electric power, is a significant part of the US economy. “Chemical products” is next in importance, followed by “computer and electronic components” which in fact ties “chemical products” in 2008 and 2009. The “petroleum and coal products” sector shows the largest variations, due presumably to the large fluctuations in the price of petroleum during this
Fig. 4. Prevalence of abstracts containing the keyword for USPO abstract filings (total over the years of 1976–2012).
R.A. Taylor et al. / International Communications in Heat and Mass Transfer 39 (2012) 1467–1473
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heat transfer can make a significant improvement in these areas, it will mean a big impact on the whole economy. In the next section we will attempt estimate this impact.
3.5. Potential value added and/or savings
Fig. 5. Historical trends of the top 4 keywords in USPO abstract filings. Note: Bars represent five year groupings during the period 1976–2010.
time period. Additionally, these sectors may have multiple supply chain 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 condensers of steam power plants. These are areas in which heat transfer contributes to the supply of electricity, but the end uses of electricity and heat might be even more important. Buildings (residential and commercial) consume approximately one third of US energy. Fig. 8 shows building energy end-use expenditures, for both 2008 and 2010, as given in the respective Buildings Energy Data Book provided by the US Department of Energy [12]. Note that the values in Fig. 8 are in 2009 $ billion for both the 2008 and the 2010 data. These data are for the entire building stock in the USA — residential and commercial. They consider not only electricity consumption, but also natural gas and other sources, such as fuel oil. “Space heating” is the largest cost, followed by “lighting,” “space cooling,” “water heating,” and “refrigeration.” Taken together these eight sectors represent a modest total contribution to the US economy — about seven percent of the total GDP. If
Calculations based on data from the EIA's Annual Energy Review indicate that, on average, US power plants had the following average conversion efficiencies in 2010: coal, 33.15%, natural gas, 44.15%, and nuclear, 32.46% [13]. In 2010 these three sources made up 89.0% of the total electrical generation market which was calculated at US $340.2 billion. This estimate was calculated by assuming 9.88 cents per kWh, including taxes which is the average retail price for electricity in 2010 according to the EIA [13]. Heat transfer research could eventually bring up the efficiency significantly in this sector, because these are nowhere near the Carnot efficiency limit. It is possible that heat transfer research could bring this efficiency up by 15–30% in the case of coal and nuclear power, and by 10–20% for natural gas electrical generation. These increases are achievable by updating aging power plants with new plants that operate at higher temperature and with those that use advanced cycles. If realized, this would represent a huge savings to the economy as the same amount of electricity could be generated with much less primary energy consumption. If we assume new technology to have roughly the same capital cost as conventional technology and that approximately 30% of the retail price is incurred from fuel costs, an annual savings of US $45 billion may be possible in the retail electric market through research and innovation. Alternatively, if current power plants can be retrofitted to achieve this order of efficiency improvement the United States could generate 480 billion kWh extra per year. This is enough to 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-use consumption, there is the potential for a direct economic benefit to be realized. It is beyond the scope of this paper to ascertain precisely the heat transfer contribution for a given sector, and its corresponding economic impact. Instead, we give only a rough estimate of the potential economic contribution of heat transfer research and innovation. We do this by assuming that improved heat transfer – stemming from heat transfer research – leads to a 10% increase in the value
Fig. 6. Value added as a percentage of USA Gross Domestic Product (GPA), for all major categories as defined by the US Bureau of Economic Analysis.
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Fig. 7. Potential improvement curve for energy conversion in the utilities (electric) sector.
added by a given sector. While this is a rough estimate, we believe that it does present a feasible potential goal for the long-term economic contribution of heat transfer research. Fig. 9 presents graphically the economic magnitude (in value-added 2010 US $ billion) of the most important sectors identified in Fig. 7 (“petroleum and coal products,” “computer and electronic products,” “chemical products,” and “utilities”) 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.” It should also be noted that a 10% improvement at end-use is worth much more than that same improvement upstream. What does Fig. 9 tell us? If one accepts that heat transfer can one day lead to a 10% improvement across the sectors where heat transfer is important, a $110 billion economic impact is possible per year. Even in the smallest sector in Fig. 9, “refrigeration,” the potential economic impact is $2.6 billion. Fig. 9 is somewhat consistent with the keywords from the NSF's awards in Fig. 2, namely, “engine” and “electronic,” suggesting that the NSF funding priorities are at least partially aligned with the nation's economic priorities. Fig. 9 might also be interpreted as a supporting argument for funding heat transfer research in fields of energy which provide the largest potential payback on investment — (i.e., the “utilities” sector), “chemical products,”
“computer and electronic products,” and so forth, with the economic justification increasing as one proceeds from left to right. 4. Conclusions The impact of heat transfer research has not been well quantified or communicated to date. A “snapshot” of recent publications in heat transfer journals, US patenting trends, and awards made by the US National Science Foundation's Thermal Transport Processes Programs, reveals the trajectory for heat transfer research. These findings are compared to sectors in the US economy that contribute to the Gross Domestic Product (GDP). From an economic point of view, the most important sectors for heat transfer research appear to be utilities (that is, energy conversion, energy efficiency, etc.), chemical products, computer and electronic products, and petroleum and coal products. Among building energy end uses, heat transfer research can have the greatest economic impact in space heating, space cooling, water heating, and refrigeration. Heat transfer research and training in the electrical utilities sector alone is estimated to potentially generate roughly $45 billion in savings for the United States or an additional 480 billion kWh supplied given today's generation capacity. If we could distribute heat transfer improvements across
Fig. 8. Distribution of building end-use expenditures in the USA.
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Fig. 9. Expected value added (10%) by heat transfer research in 2010 ($ billions).
all sectors, it would be possible to generate economic ‘value added’ on the 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. References [1] A.A. Toole, The impact of public basic research on industrial innovation: evidence from the pharmaceutical industry, Research Policy 41 (1) (Jul. 2011) 1–12. [2] W.M. Cohen, R.R. Nelson, J.P. Walsh, Links impacts: the influence of public research on industrial R&D, Management Science 48 (1) (2002) 1–23. [3] D.A. King, The scientific impact of nations: what different countries get for their research spending, Nature 430 (15) (July 2004) 310–316. [4] A. Salter, The economic benefits of publicly funded basic research: a critical review, Research Policy 30 (3) (Mar. 2001) 509–532. [5] A. Geuna, L. Nesta, University patenting and its effects on academic research: the emerging European evidence, Research Policy 35 (6) (Jul. 2006) 790–807.
[6] G.F. Nemet, D.M. Kammen, U.S. energy research and development: declining investment, increasing need, and the feasibility of expansion, Energy Policy 35 (1) (Jan. 2007) 746–755. [7] F. Narin, K.S. Hamilton, D. Olivastro, The increasing linkage between U.S. technology and public science, Research Policy 26 (1997). [8] NSF, Academic R&D expenditures. [Online]. Available: http://www.nsf.gov/statistics/ rdexpenditures/2012. [9] B. Martin, et al., The Relationship Between Publicly Funded Basic Research and Economic Performance: A SPRU Review, HM Treasury, 1996. [10] WIPO, Patent applications by patent office and country of origin (1995–2010). [Online]. Available: http://www.wipo.int/ipstats/en/statistics/patents/2012. [11] USPTO, US Patent Full-Text Data Base. [Online]. Available: http://patft.uspto.gov/ netahtml/PTO/search-bool.html2012. [12] DOE, Buildings Energy Data Book, US Department of Energy. [Online]. Available: http://buildingsdatabook.eren.doe.gov/DataBooks.aspx. [13] EIA, Annual energy statistics. [Online]. Available: http://205.254.135.7/totalenergy/ data/annual/index.cfm#electricity2011.
Contents lists available at SciVerse ScienceDirect
International Communications in Heat and Mass Transfer journal homepage: www.elsevier.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, Australia Arizona State University, Tempe, AZ, USA c The University of Tulsa, Tulsa, OK, USA d US Department of Energy, Washington DC, USA e Phelan Research Solutions, Inc., Scottsdale, AZ, USA b
a r t i c l e
i n f o
Available online 20 September 2012 Keywords: Research Impacts Economy Patents Publishing
a b s t r a c t Heat transfer research affects almost every sector of the economy, yet its impacts have not been well studied or communicated to date. To address this issue, this article evaluates recent heat transfer research trends and which parts 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 research helps to attain a 10% conversion efficiency gain in all relevant sectors of the US economy, ~110 billion dolars of annual value added could be generated. © 2012 Elsevier Ltd. All rights reserved.
1. Introduction What is the impact of heat transfer research? Additionally, what type of heat transfer research should be pursued? There is a growing body of evidence which partially answers these questions for research in general [1–7], but very little has been published specifically for heat transfer research. Discussion of the questions above is imperative because it provides a potential avenue for researchers to engage the broader technical and non-technical community. This is not well done in the thermal sciences at present. While developments in cholesterol or pain medication and advancements in refrigeration technology are both significant to society, pharmaceutical research results are disseminated much more broadly. To help address these issues, we will briefly review the case for research in general, followed by an examination of the field of heat transfer research today and how it contributes to the US economy. This analysis will rely on key measureable inputs and outputs of heat transfer research. Our objective here is not to draw firm conclusions about where or how much research funding should be allocated, but rather to contribute to a dialogue about the role of heat transfer research in society at large. We propose that by discussing the impacts of their work, researchers can better communicate what is to be gained from investing resources in heat transfer research. To give one anecdotal example, a number of ‘non-heat transfer’ academic colleagues at one of the co-author's institutions were largely unaware of the connection between heat transfer and energy research. This implies that either: a) heat transfer research is not ☆ Communicated by W.J. Minkowycz. ⁎ Corresponding author. E-mail address: [email protected] (R.A. Taylor). 0735-1933/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.icheatmasstransfer.2012.09.007
making contributions to global energy challenges, OR, b) the link between heat transfer research and energy issues is not being discussed — even with other members of academia. We suggest the latter implication is more likely since heat transfer processes are integral to almost all energy systems, including: heating/cooling of buildings, automobiles, and power plants. University researchers are largely free to investigate any avenue they prefer, but many times research is steered towards potential funding opportunities. This indicates that funding agencies – public (e.g. the US National Science Foundation or the Australian Research Council) and private (e.g. charitable organizations or corporate R&D programs) – essentially determine what research gets done. At times, special programs are formed to address particular issues or to fulfill the mission of the particular agency (e.g. ARPA-E's HEATS program or the Australian Solar Institute's United States-Australia Solar Energy (USASEC) Collaboration). On such occasions, research impacts can be quantified by how well the program objectives were addressed. While many of these types of programs are available, they represent only one part of the funding available for heat transfer research. Regardless of the drivers for research, it is important to determine what society gets from research — i.e. what is its value? Answering this question – and communicating those answers – is essential because up to 60% 1 of US heat transfer research funding comes from federal sources (i.e. taxpayers) [8]. We suggest that even in the absence of formal, well-defined programs, heat transfer research is fundamentally focused on solving problems that are important to society. One potential way to improve
1 Based on the 200–2010 funding proportion for Engineering research — this proportion is in decline [8].
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communication is to discuss the historical impacts of heat transfer research. Additionally, if we want heat transfer research to have a substantial impact, it is logical to focus efforts on sectors/areas which can provide the biggest socioeconomic return on research investment. That said, how can decisions potentially be made as to what sectors of the economy and what challenges are worthy of funding resources? The following sections should shed some light on this question and the others posed above. 2. General impact of research In this section we provide a brief background of the general impacts of research which also, presumably, hold true for heat transfer research. It is a general notion that research benefits a nation's economic competitiveness. In 2004, King presented a comprehensive analysis of research output as measured by publications, citations, and the top 1% highly cited publications [3]. This was compared with a nation's economic strength [3]. In general a positive correlation 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 considerable scatter. Smaller European nations like Switzerland, Sweden, and Israel have a higher citation intensity than the US and Japan. It is also clear from this article that research is heavily concentrated 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 research was 20 to 40%, although this may be declining [4]. They noted that publically funded research benefits companies in different ways, i.e., pharmaceutical companies see direct benefits, while automotive companies derive benefits largely by the training provided by academic research. There is also an important geographical dimension, in that firms located near research centers derive greater benefit than those further away. Also, academic research seems to encourage industrial research, but not vice versa. With regard to the direct economic impact of research, Nemet and Kammen [6] and Toole [1] point to the connection between the number of patents generated in a particular field [6], or the products generated by the pharmaceutical industry [1] [4], and the amount of research and development funding. Given that Nemet and Kammen [6] specifically address the field of energy, this is highly relevant for heat transfer research. Overall, benefits of research (privately and publically 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 problemsolving • Creating new firms An investigation comparable to Refs. [3–6] on the impact of heat transfer research has not, to our knowledge, been presented. This article will provide the requisite background and point out the most important areas for future comprehensive investigations in heat transfer research.
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: Applied Thermal Engineering (ATE), International Communications in Heat and Mass Transfer (ICHMT), Journal of Heat Transfer (JHT), International Journal of Thermal Sciences (IJTS), and International Journal of Heat and Mass Transfer (IJHMT). Approximately 7500 research articles were 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 transfer literature during this time frame. A list of ‘salient’ keywords for analysis was chosen by examining the actual keywords for every article in IJHMT between 2007 and 2011. In IJHMT during this period, common keywords are ‘heat’, ‘transfer’, ‘flow’, ‘thermal’, ‘method’, and ‘mass’ — which appear approximately1400, 900, 700, 370, 330, 300, and 150 times, respectively. It should be noted that the words ‘heat’, ‘transfer’, and ‘mass’ are redundant for authors to use as official keywords since those already appear in the journal name. While these commonly used keywords might be informative in patenting, they do little to distinguish themselves amongst heat transfer research articles. As such, we analyze only the most commonly occurring ‘salient‘ keywords from this list — i.e. those which specify the type of heat transfer research accomplished in the article. Fig. 1 presents a how often these keywords appear in the titles of these journals during over five full years (2007–2011). The composite bars indicate how this research is distributes between journals. Somewhat surprisingly, the word “porous” is found to be the most prevalent ‘salient’ word in the abstracts of these journals, but more than half of them come from one journal (IJHMT). The next most frequently used word in abstracts is “cooling,” followed in turn by “heat exchanger,” “microchannel,” “nanofluid,” “refriger,” 2 “engine,” and so forth. Other words that appear are “solar,” “electronic,” and “nanoparticle,” indicating the continuing or recent emphasis on these fields. Fig. 2 shows trends in the occurrence of the most popular of these words over the five year period. Many of these words show an increase in frequency over time. The most noticeable increase over time is found in the word ‘nanofluid’ — which goes from 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 recent NSF awards (2006–2011). It is interesting that “engine” is the most cited word, since it is not used as frequently in journal publications. It should be noted that the frequency of ‘engine’ drops off considerably for NSF awards in 2010 and 2011 from its peak in 2008. Following “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 journal keywords, it is well down the list in terms of NSF-supported awards. There is clearly some correlation between the words found in research grants and those that appear in publications (e.g., “engines” and “cooling”), but the correlation is not perfect. One simple explanation for this is that ‘developing the knowledge base’ (i.e. publishing research articles) is just one of the criteria for deciding which research deserves funding. If this were indeed the only criterion, research would likely have a low return on investment.
3. The field of heat transfer research today 3.3. Heat transfer patents What is the current direction of the majority of heat transfer research? We propose the following three measures should yield a “snapshot” of current research efforts: a search for keywords in the titles and abstracts of papers published in heat transfer journals, awards granted by the Thermal Transport Processes Program of the US National Science Foundation (NSF), and patent filings.
A third key measure of the impact of heat transfer research is the invention of new products, technology, and improved designs. A good estimate of the impact in this area can be determined from the 2
“Refriger” is used to capture “refrigerant,” “refrigeration,” “refrigerate,” etc.
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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 Heat and Mass Transfer).
number of patents filed. The US Patent Office provides a good subset of this activity since the United States patent historically grants a large fraction of the world's patents — although Japan's patent office has issued more several times since 1995 [10]. Fig. 4 shows the prevalence of heat transfer keywords from above as they appear in patent abstracts according to a keyword search of the USPTO full text and image data base, which lists patents from 1976 onwards [11]. To put this in perspective, since 1976 there have been about 4.66 million total patents issued and the word ‘heat’ appears in about 3.4% of the abstracts, while ‘engine’ and thermal have appeared in 2.2% and 1.6% of the abstracts, respectively [11]. It should be noted that many of the heat transfer words are much more prevalent than ‘pharmaceutical’ or ‘medical’ which appear in 0.8% and 0.6% of all US patent abstracts, respectively. Fig. 5 shows the frequency of occurrence of the top four heat transfer words in abstracts since 1976 (given in
5 year spans). For each of these words, the five year period from January 2000 to December 2004 represented the peak in occurrence. It should also be noted that total US patents followed a similar arc with a peak between 2000 and 2004, presumably due to US economic conditions in recent years. 3.4. Economics and heat transfer In this section, we will estimate the economic impact of heat transfer research. To do so, we limit ourselves to the US economy, and in particular focus on how different sectors contribute to the GDP — the traditional measure of a nation's economic strength. It is first instructive to examine the relative contributions of all major sectors 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
Fig. 2. Prevalence of heat transfer article titles containing the most prominent ‘salient’ keywords in the recent years 2007–2011.
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Fig. 3. Yearly variation in the prevalence of NSF-awarded grant abstracts containing the keywords (Engineering Directorate, Chemical, Bioengineering, Environmental and Transport Systems (CBET) Division, Thermal Transport Processes Program).
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. The sectors with the greatest contribution are “finance, insurance, real estate, rental, and leasing,” but of course heat transfer does not play much of a role in these sectors. Nonetheless, Fig. 6 gives a good sense of relative weight of each sector. Manufacturing is the largest sector where heat transfer plays some role, but this role is only a minor one. Fig. 6 also shows that in contrast to the long-term trend there is a small uptick from 2009 to 2010 in the manufacturing sector. In what sectors can heat transfer be considered to play a major role? Based upon the categorization provided by the BEA, and delving deeper into its subcategories (that is, not limiting ourselves to just the major categories shown in Fig. 5), we consider the following sectors to have significant roles for heat transfer: • Utilities • Chemical products
• • • • • •
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 categories given by the BEA which, in our judgment, include a significant heat transfer component. The value added as percent of GDP for these particular categories are given in Fig. 6. The “utilities” sector is near the top of this graph, ranging between 1.6% and 1.8% of GDP. This indicates that energy conversion, from a fuel to electric power, is a significant part of the US economy. “Chemical products” is next in importance, followed by “computer and electronic components” which in fact ties “chemical products” in 2008 and 2009. The “petroleum and coal products” sector shows the largest variations, due presumably to the large fluctuations in the price of petroleum during this
Fig. 4. Prevalence of abstracts containing the keyword for USPO abstract filings (total over the years of 1976–2012).
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heat transfer can make a significant improvement in these areas, it will mean a big impact on the whole economy. In the next section we will attempt estimate this impact.
3.5. Potential value added and/or savings
Fig. 5. Historical trends of the top 4 keywords in USPO abstract filings. Note: Bars represent five year groupings during the period 1976–2010.
time period. Additionally, these sectors may have multiple supply chain 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 condensers of steam power plants. These are areas in which heat transfer contributes to the supply of electricity, but the end uses of electricity and heat might be even more important. Buildings (residential and commercial) consume approximately one third of US energy. Fig. 8 shows building energy end-use expenditures, for both 2008 and 2010, as given in the respective Buildings Energy Data Book provided by the US Department of Energy [12]. Note that the values in Fig. 8 are in 2009 $ billion for both the 2008 and the 2010 data. These data are for the entire building stock in the USA — residential and commercial. They consider not only electricity consumption, but also natural gas and other sources, such as fuel oil. “Space heating” is the largest cost, followed by “lighting,” “space cooling,” “water heating,” and “refrigeration.” Taken together these eight sectors represent a modest total contribution to the US economy — about seven percent of the total GDP. If
Calculations based on data from the EIA's Annual Energy Review indicate that, on average, US power plants had the following average conversion efficiencies in 2010: coal, 33.15%, natural gas, 44.15%, and nuclear, 32.46% [13]. In 2010 these three sources made up 89.0% of the total electrical generation market which was calculated at US $340.2 billion. This estimate was calculated by assuming 9.88 cents per kWh, including taxes which is the average retail price for electricity in 2010 according to the EIA [13]. Heat transfer research could eventually bring up the efficiency significantly in this sector, because these are nowhere near the Carnot efficiency limit. It is possible that heat transfer research could bring this efficiency up by 15–30% in the case of coal and nuclear power, and by 10–20% for natural gas electrical generation. These increases are achievable by updating aging power plants with new plants that operate at higher temperature and with those that use advanced cycles. If realized, this would represent a huge savings to the economy as the same amount of electricity could be generated with much less primary energy consumption. If we assume new technology to have roughly the same capital cost as conventional technology and that approximately 30% of the retail price is incurred from fuel costs, an annual savings of US $45 billion may be possible in the retail electric market through research and innovation. Alternatively, if current power plants can be retrofitted to achieve this order of efficiency improvement the United States could generate 480 billion kWh extra per year. This is enough to 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-use consumption, there is the potential for a direct economic benefit to be realized. It is beyond the scope of this paper to ascertain precisely the heat transfer contribution for a given sector, and its corresponding economic impact. Instead, we give only a rough estimate of the potential economic contribution of heat transfer research and innovation. We do this by assuming that improved heat transfer – stemming from heat transfer research – leads to a 10% increase in the value
Fig. 6. Value added as a percentage of USA Gross Domestic Product (GPA), for all major categories as defined by the US Bureau of Economic Analysis.
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Fig. 7. Potential improvement curve for energy conversion in the utilities (electric) sector.
added by a given sector. While this is a rough estimate, we believe that it does present a feasible potential goal for the long-term economic contribution of heat transfer research. Fig. 9 presents graphically the economic magnitude (in value-added 2010 US $ billion) of the most important sectors identified in Fig. 7 (“petroleum and coal products,” “computer and electronic products,” “chemical products,” and “utilities”) 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.” It should also be noted that a 10% improvement at end-use is worth much more than that same improvement upstream. What does Fig. 9 tell us? If one accepts that heat transfer can one day lead to a 10% improvement across the sectors where heat transfer is important, a $110 billion economic impact is possible per year. Even in the smallest sector in Fig. 9, “refrigeration,” the potential economic impact is $2.6 billion. Fig. 9 is somewhat consistent with the keywords from the NSF's awards in Fig. 2, namely, “engine” and “electronic,” suggesting that the NSF funding priorities are at least partially aligned with the nation's economic priorities. Fig. 9 might also be interpreted as a supporting argument for funding heat transfer research in fields of energy which provide the largest potential payback on investment — (i.e., the “utilities” sector), “chemical products,”
“computer and electronic products,” and so forth, with the economic justification increasing as one proceeds from left to right. 4. Conclusions The impact of heat transfer research has not been well quantified or communicated to date. A “snapshot” of recent publications in heat transfer journals, US patenting trends, and awards made by the US National Science Foundation's Thermal Transport Processes Programs, reveals the trajectory for heat transfer research. These findings are compared to sectors in the US economy that contribute to the Gross Domestic Product (GDP). From an economic point of view, the most important sectors for heat transfer research appear to be utilities (that is, energy conversion, energy efficiency, etc.), chemical products, computer and electronic products, and petroleum and coal products. Among building energy end uses, heat transfer research can have the greatest economic impact in space heating, space cooling, water heating, and refrigeration. Heat transfer research and training in the electrical utilities sector alone is estimated to potentially generate roughly $45 billion in savings for the United States or an additional 480 billion kWh supplied given today's generation capacity. If we could distribute heat transfer improvements across
Fig. 8. Distribution of building end-use expenditures in the USA.
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Fig. 9. Expected value added (10%) by heat transfer research in 2010 ($ billions).
all sectors, it would be possible to generate economic ‘value added’ on the 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. References [1] A.A. Toole, The impact of public basic research on industrial innovation: evidence from the pharmaceutical industry, Research Policy 41 (1) (Jul. 2011) 1–12. [2] W.M. Cohen, R.R. Nelson, J.P. Walsh, Links impacts: the influence of public research on industrial R&D, Management Science 48 (1) (2002) 1–23. [3] D.A. King, The scientific impact of nations: what different countries get for their research spending, Nature 430 (15) (July 2004) 310–316. [4] A. Salter, The economic benefits of publicly funded basic research: a critical review, Research Policy 30 (3) (Mar. 2001) 509–532. [5] A. Geuna, L. Nesta, University patenting and its effects on academic research: the emerging European evidence, Research Policy 35 (6) (Jul. 2006) 790–807.
[6] G.F. Nemet, D.M. Kammen, U.S. energy research and development: declining investment, increasing need, and the feasibility of expansion, Energy Policy 35 (1) (Jan. 2007) 746–755. [7] F. Narin, K.S. Hamilton, D. Olivastro, The increasing linkage between U.S. technology and public science, Research Policy 26 (1997). [8] NSF, Academic R&D expenditures. [Online]. Available: http://www.nsf.gov/statistics/ rdexpenditures/2012. [9] B. Martin, et al., The Relationship Between Publicly Funded Basic Research and Economic Performance: A SPRU Review, HM Treasury, 1996. [10] WIPO, Patent applications by patent office and country of origin (1995–2010). [Online]. Available: http://www.wipo.int/ipstats/en/statistics/patents/2012. [11] USPTO, US Patent Full-Text Data Base. [Online]. Available: http://patft.uspto.gov/ netahtml/PTO/search-bool.html2012. [12] DOE, Buildings Energy Data Book, US Department of Energy. [Online]. Available: http://buildingsdatabook.eren.doe.gov/DataBooks.aspx. [13] EIA, Annual energy statistics. [Online]. Available: http://205.254.135.7/totalenergy/ data/annual/index.cfm#electricity2011.