Development Of Refrigeration Technology Research Articles

Large room-temperature electrocaloric response achieved by tailoring the first-order orthorhombic-tetragonal phase transition in BaTiO3-based ferroelectric ceramics

The development of refrigeration technology has burgeoned in response to the challenges posed by global warming. Notably, electrocaloric materials have garnered significant attention for their potential in miniaturization and high efficiency. However, investigations into the electrocaloric response in proximity to orthorhombic-tetragonal phase transition in BaTiO3-based ferroelectric ceramics remain scarce. In this study, we employ a lead-free x(Ba0.7Sr0.3)TiO3-(1-x)Ba(Zr0.2Ti0.8)O3 polycrystalline ceramics fabricated through the solid-state reaction method. The comprehensive analysis includes elucidation of the phase structure, surface morphologies, dielectric properties, domain switching behavior, and the electrocaloric effect. Integrating these findings with the phase diagram unveils optimal adiabatic temperature change (ΔT) achieved within the quadruple point coexistence region. That is, the highest ΔT of 0.53 K is achieved for x = 0.4 ceramic, which is attributed to the increased entropy resulting from multiple polar phases. Remarkably, the highest ΔT of 0.3 K is attained in x = 0.6 ceramic under a low driving electric field of 30 kV/cm at room temperature, precisely within the orthorhombic-tetragonal transition temperature. The investigation underscores the efficacy of regulating the first-order orthorhombic-tetragonal phase transition to achieve exceptional electrocaloric responses at room temperature.

Research progress in magnetocaloric effect materials

Magnetocaloric effect（MCE) is the intrinsic property of a magnetic material near transition temperature and the magnetic refrigeration based on MCE has been demonstrated as a promising alternative to the conventional gas compression or expansion refrigeration due to its high energy efficiency and environmental friendliness. The development of magnetic refrigeration technology depends on the research progress of magnetic refrigerant materials with large MCEs. Lots of researches of material exploration and material optimization have promoted the progress of magnetic refrigeration technology in recent decades. In this paper, we introduce the basic theory of MCE and the development of refrigeration technology, review the research progress of large MCE materials both in low temperature range and in room temperature range, and specifically focus on the latest progress of some MCE materials. Low temperature MCE materials mainly include those rare earth based materials with low transition temperatures, such as binary alloys（RGa, RNi, RZn, RSi, R3Co and R12Co7), ternary alloys（RTSi, RTAl, RT2Si2, RCo2B2 and RCo3B2), and quaternary alloys（RT2B2C), where R denotes the rare earth and T represents the transition metal. Those materials mainly possess the second-order phase transitions and show good thermal hysteresis, magnetic hysteresis, and thermal conductivities. Room temperature MCE materials are mainly Gd-Si-Ge intermetallic compounds, La-Fe-Si intermetallic compounds, MnAs-based compounds, Mn-based Heusler alloys, Mn-based antiperovskite compounds, Mn-Co-Ge intermetallic compounds, Fe-Rh compounds, and perovskite-type oxides. The above materials usually have the first-order phase transitions and most of these materials possess the large MCEs in room temperature range, therefore they have received much attention home and abroad. Among those room temperature MCE materials, the La-Fe-Si series is considered to be the most promising magnetic refrigerant materials universally and our country has independent intellectual property rights of them. The further development prospects of MCE materials are also discussed at the end of this paper.

Daniel Willard and Progressive Management on the Baltimore & Ohio Railroad by David M. Vrooman

432 Book Reviews TECHNOLOGY AND CULTURE has been larger, more widely distributed, and less oriented to appli­ cations, but in both Germany and France funding has shifted from the promotion of science to the promotion of industry and particular industrial regions. In science, instances of successful bilateral cooper­ ation (on the order of the physical research at Grenoble) have been rare. Cooperation has been minimal in armaments, as Ulrich Albert points out, and unimpressive in nuclear power, as Joachim Radkau notes in considering the failure of the high-flying EURATOM concept of the 1960s. In the auto industry, the joint ventures described by Patrick Fridenson were mostly failures, and Gottfried Plumpe notes that cooperation in the chemical industry was mostly restricted to the establishment of subsidiary companies. A final set of papers is concerned with historians and their tools: Maurice Hamon presents an overview of French industrial archives, and Otto Mayr upholds the necessity of presenting history in techno­ logical museums. The volume concludes with bibliographical sugges­ tions and a useful directory of French-German organizations, but there are no general observations on bilateral relations between the two continental industrial powers. The history of American-German relations in technology, science, and industry is of similar importance to the Franco-German relationship, yet tbis subject has not been addressed in any systematic fashion. Where could such an address take place? Maybe again at the Deutsches Museum? Hans-Liudger Dienel Mr. Dienel is with the Deutsches Museum. He has submitted a Ph.D. dissertation comparing the interplay of academia and industry in the development of refrigeration technology in Germany and the United States, 1870-1930. In 1990 he organized a session on national technological styles for the SHOT meeting in Cleveland. Daniel Willard and Progressive Management on the Baltimore & Ohio Railroad. By David M. Vrooman. Columbus: Ohio State University Press, 1991. Pp. xvi + 218; illustrations, notes, index. $40.00. In this book, David Vrooman interprets employee welfare pro­ grams at the Baltimore & Ohio Railroad as the product of the personal character of Daniel Willard, who served as president of the line from 1910 until 1942. Characterizing corporate welfare work as “a humanistic movement with liberalJudeo-Christian roots” that “had as its goal the full development of the individual and collective human potential (nothing less than that) of a firm’s employees through disciplined, energetic, socially oriented clean living” (pp. 18—19), Vrooman argues that the B&O pursued it more vigorously and more successfully than other railroads. He attributes this to Willard’s “bedrock respect for the intrinsic value and dignity of his employees” (p. 7). “Daniel Willard was the embodiment of the principle that TECHNOLOGY AND CULTURE Book Reviews 433 managerial effectiveness is, in its origin, a function not so much of technique as of character” (p. x). Convinced that Willard’s welfare programs contributed substantially to the fortunes of the B&O, Vrooman determines that other firms spurned them only because they lacked “a leader like Daniel Willard” (p. xv). “Better than any other man in his industry and in his time, and arguably as well as anyone in any industry and in any time,” Vrooman concludes, “he showed how to lead a company” (p. 183). This is a heavy burden to load on any subject, and the body of this study shows the strain. Rather thanjust describe welfare programs at the B&O, Vrooman struggles throughout to portray and analyze them in a fashion that justifies his assessment of Willard. The record, unfortunately, does not readily yield to such an analysis. Most of the welfare programs pursued by the B&O could be found on many other lines. The single exception was the B&O’s Cooperative Plan, which beginning in 1923 provided a forum for managers and workers to exchange ideas about the workplace. This plan attracted considerable publicity at the time, and Vrooman devotes two of his four main chapters to it. Impetus for the Cooperative Plan came not from Willard, however, but from the labor leader Otto Beyer. Willard agreed to try it in the B&O’s most militant shops following the 1922 rail strike. Though employees at additional shops soon joined in, the plan had little impact on other types of workers, in part because Willard showed no enthusiasm for...

Archaeology of the Old Iceworks, 35 Hunter Street, Hobart

The invention and development of refrigeration technology in the second half of the 19th century was a crucial factor in the success of Australia's meat export trade, although in Tasmania it was the fruit trade which made the most use of it. The Henry Jones and cold-storage facility at 35 Hunter Street, Hobart, was probably established in 1903, involving extensive alterations to the existing building. Six of the seven insulated rooms in the building still contained refrigerant piping in 1986. This represented about one-twentieth of the volume of the original facility and was mostly used for cold storage. However, there is also evidence that most, if not all of the firm's ice-making took place on this site. The Old Iceworks was an important component of the industrial and commercial development of Hobart. Its remains were representative of refrigerating technology and equipment found throughout Australia in the early 20th century and were the last surviving ammonia iceworks in Tasmania.