Energy and exergy analysis of a desiccant cooling system integrated with thermal energy storage and photovoltaic/thermal-solar air collectors

This paper presents an energy and exergy analysis of a desiccant cooling system integrated with an air-based thermal energy storage (TES) unit using phase change materials (PCMs) and a photovoltaic/thermal-solar air collector (PV/T-SAC). The PV/T-SAC was used to generate thermal energy for desiccant wheel regeneration and space heating, and the TES was used to solve the mismatch between thermal energy supply and demand. The performance of this system was evaluated using a simulation system developed using TRNSYS. The effects of several key parameters on solar thermal contribution, specific net electricity generation, and the exergy destructions of individual components and overall system were investigated. It was found that the system exergy destruction was mainly resulted by the PV/T-SAC. Both the exergy performance and energy performance of this system were significantly influenced by the length and PV factor of the PV/T-SAC used. The results obtained from this study could be potentially used to guide the optimal design of desiccant cooling systems integrated with thermal energy storage and solar energy systems

Solar-Assisted HVAC Systems with Integrated Phase Change Materials

Solar-assisted heating, ventilation and air-conditioning (HVAC) systems are receiving increasing attention. This chapter presents the development of HVAC systems with integrated solar photovoltaic-thermal (PVT) collectors and phase change materials (PCMs) to reduce building energy consumption while providing satisfactory indoor thermal comfort. PVT collectors, which can generate both thermal energy and electricity simultaneously, are a promising technology for developing high-performance buildings. As solar energy is intermittent, the integration of phase change materials (PCMs) with PVT-driven HVAC systems can provide an opportunity to effectively utilise solar energy and maximise the performance of HVAC systems. The results showed that the coefficient of performance (COP) of an air source heat pump system with integrated PVT collectors and PCMs was 5.2, which was higher than the use of the air source heat pump only (i.e., 3.06) during the test period investigated

Solar Thermal Energy Storage Using Paraffins as Phase Change Materials for Air Conditioning in the Built Environment

Thermal energy storage (TES) using phase change materials (PCMs) has received increasing attention since the last decades, due to its great potential for energy savings and energy management in the building sector. As one of the main categories of organic PCMs, paraffins exhibit favourable phase change temperatures for solar thermal energy storage. Its application is therefore effective to overcome the intermittent problem of solar energy utilisation, thereby reducing the power consumption of heating, ventilation and air conditioning (HVAC) systems and domestic hot water (DHW) systems. This chapter reviews the development and performance evaluation of solar thermal energy storage using paraffin-based PCMs in the built environment. Two case studies of solar-assisted radiant heating and desiccant cooling systems with integrated paraffin-based PCM TES were also presented. The results showed that paraffin-based PCM TES systems can rationalise the utilisation of solar thermal energy for air conditioning while maintaining a comfortable indoor environment

Questions Involving National Peace and Harmony or Injured Plaintiff Litigation ? The Original Meaning of Cases in Article III of the Constitution

If a federal official is deliberately violating the Constitution, is it possible no federal court has the power to halt that conduct? Federal judges have been answering “yes” for more than a century— dismissing certain kinds of lawsuits alleging unconstitutional conduct by ruling the lawsuits were not “cases” as meant in the phrase “[t]he Judicial Power shall extend to all Cases” in Article III, Section Two, of the Constitution. For example, in July 2019, the U.S. Court of Appeals for the Fourth Circuit dismissed a lawsuit that the State of Maryland and the District of Columbia brought against President Donald Trump claiming he is deliberately violating the Constitution’s prohibition against receiving emoluments from foreign states. The lawsuit alleged that foreign governments pay substantial sums for using the Trump International Hotel in Washington D.C. and that President Trump is sole owner of the Trump Organization, which in turn owns that hotel. The court said: “[T]he District and Maryland’s interest in constitutional governance is no more than a generalized grievance, insufficient to amount to a case or controversy within the meaning of Article III.” In 1911, the United States Supreme Court declared: “[T]he exercise of the judicial power is limited to ‘cases’ and ‘controversies.’ . . . By cases and controversies are intended the claims of litigants . . . . The term implies the existence of present or possible adverse parties, whose contentions are submitted to the court for adjudication.” The Supreme Court subsequently further specified the meaning of “case” within the meaning of Article III to include the following “essential core”: a plaintiff who has suffered a concrete and particularized injury that is likely to be redressed by a judicial decision. Thus, at least in the civil setting, the Court has restricted the meaning of “cases” to adversary litigation initiated by a plaintiff with a personal and concrete injury— in brief, “injured plaintiff litigation.” The claims of Maryland and the District of Columbia against President Trump were dismissed by the Fourth Circuit without consideration of the merits because, in the court’s view, the plaintiffs had failed to show “concrete and particularized” injury that was different than the alleged harm suffered by all citizens if the President is corrupted by receipt of foreign payments. Failure to meet the Supreme Court’s definition of “case” is described as a “lack of standing.” Responding to the argument that if the District of Columbia and Maryland “could not obtain judicial review of [the President’s] action, ‘then as a practical matter no one can[,]’” the Fourth Circuit cited the answer provided in a 1974 Supreme Court decision: “[The] assumption that if [the plaintiffs] have no standing to sue, no one would have standing, is not a reason to find standing.” The empirical research reported in this article suggests that this “injured plaintiff litigation” interpretation of the meaning of “cases” may be more narrow—perhaps indeed entirely different—than how the word in its Article III context would have been used and understood by those who drafted and ratified the Constitution. For the first two months of a constitutional convention that lasted less than three-and-a-half months, various versions of what would eventually become Section Two of Article III consistently provided that federal courts should have the power to “hear and determine . . . questions which may involve the national peace and harmony.” On July 18, 1787, the Convention unanimously adopted the following resolution proposed by James Madison: “[T]he jurisdiction of the national Judiciary shall extend to cases arising under laws passed by the general Legislature, and to such other questions as involve the National peace and harmony.” The authors of this article, comprised of a research team of lawyers and linguists, used a variety of computer-aided methods for examining very large data sets of Founding Era texts to explore linguistic implications suggested to them by Madison’s July 18 resolution. This research indicated that those who drafted and ratified the Constitution: Would have understood “cases arising under laws” to be a type or example of “questions as involve the National peace and harmony”; Would have understood “such other questions” to be a more general category of jurisdiction than “cases arising under laws”; and Would not have understood “cases” as having a stable, inherent meaning such as “injured plaintiff litigation”—instead “cases” in each context of use in Article III would have been read as having a different meaning, constructed through its combination with accompanying words

Bridging Corpus Linguistics to ITA Training and Testing: Validation of Functional Language in Academic Lectures

Corpus linguistics studies on academic discourse provide valuable insights on linguistic patterns between form, meaning, and functions of the language used in natural academic discourses. Among those, lectures have been one of the most studied spoken academic genres, especially from a corpus linguistics perspective (e.g., Deroey, 2012; Deroey & Taverniers, 2012; Chang, 2012). These studies especially contribute to the training and inclusion process of non-native English-speaking participants in English-dominant academic discourses. However, there is a paucity of discussion linking corpus linguistics findings to materials or methods for training non-native speaking instructors. Besides, although corpus-informed language features have started to emerge as potential constructs in language testing of non-native speaking instructors (e.g., Römer, 2017), no empirical evidence has shown the relationship between the linguistic features discussed in corpus studies of academic lectures and the perceived quality of those lectures. This issue becomes increasingly pertinent to the population of international teaching assistants (ITAs), whose academic trajectories are dependent on ITA placement tests that assess how they use language to teach. Therefore, study 1 in this dissertation presents a systematic review of corpus studies on academic lectures in the past decades, revealing three main types of linguistic units employed in these analyses. This review serves as a foundation to the following empirical studies. Study 2 , which validates the use of frequency-based functional units as an assessment construct in evaluating international teaching assistants\u27 test performances, especially in tasks where they perform a teaching demonstration of an academic lecture. reports a quantitative analysis that investigates the relationship between language proficiency, functional language use, and overall perceived teaching effectiveness. The third empirical study investigates the relationship between ITAs\u27 functional language use and students\u27 attitudes towards the ITAs. This study is motivated by sociolinguistics studies on language attitudes. The results of this dissertation facilitate a better understanding of the use of functional language in lectures and provide insights on directions for future corpus linguistics research on academic lectures to improve assessment and training of non-native instructors

Development, Modelling and Performance Assessment of Phase Change Enhanced Desiccant Cooling

Energy consumption and greenhouse gas emission of the building sector have been continuously increasing in recent decades due to the population growth and demand for better indoor thermal comfort. Desiccant cooling is an attractive option for tackling these challenges as desiccant cooling systems are mainly driven by low-grade thermal energy and consume less electricity and fossil fuels as compared to conventional vapour-compression air-conditioning systems. On the other hand, phase change materials (PCMs) with the ability to provide high energy storage densities and the characteristics to store thermal energy at a relatively constant temperature have attracted increasing attention for developing high-performance air-conditioning systems. This thesis aims at developing, evaluating and optimising phase change enhanced desiccant cooling systems. Two novel approaches to enhancing the desiccant cooling system with PCMs were developed, including a desiccant wheel cooling system using hybrid photovoltaic/thermal-solar air collector (PV/T-SAC) and PCM thermal energy storage (TES) unit, and a liquid desiccant dehumidifier using a new phase change enhanced desiccant solution..

A review of heating, ventilation and air conditioning technologies and innovations used in solar-powered net zero energy Solar Decathlon houses

Innovations in Heating, Ventilation, and Air Conditioning (HVAC) systems are continuously required to provide a better, healthier and more productive and sustainable built environment for building occupants with minimized energy or cost consumption. This paper provides an overview of the HVAC technologies and systems used in 212 solar-powered houses developed through 13 U.S. Department of Energy Solar Decathlon (SD) competitions. Some comments and discussions on the HVAC technologies and systems used in the SD competitions were also provided. The review was carried out based on the information available from the organizer\u27s project reports and equipment summary, team project manuals, and construction drawings available on the SD official websites as well as the published research papers and textbooks. It was found that 84.9% and 89.6% of the competition teams used heat pumps for space heating and space cooling, respectively, among which air-to-air heat pumps were used by approximately 50% of the competition teams. A wide range of energy technologies such as phase change materials, night-time radiative cooling, evaporative cooling, desiccant dehumidification, and energy/heat recovery ventilators have been used to reduce the electricity consumption of the HVAC systems. Energy/heat recovery ventilators were used by more than 55% of the teams in each competition held after 2005. Phase change materials were also frequently used in the competitions held in Europe. The SD competitions provided an excellent platform to showcase innovations of the HVAC technologies in residential buildings