Salt impregnated desiccant matrices for ‘open’ thermochemical energy conversion and storage: improving energy density utilisation through hygrodynamic & thermodynamic reactor design

In this study, the performance of three nano-composite energy storage absorbents; Vermiculite-CaCl2 (SIM-3a), Vermiculite-CaCl2-LiNO3 (SIM-3f), and the desiccant Zeolite 13X were experimentally investigated for suitability to domestic scale thermal energy storage. A novel 3 kWh open thermochemical reactor consisting of new meshed tube air diffusers was built to experimentally examine performance. The results were compared to those obtained using a previously developed flatbed experimental reactor. SIM-3a has the best cyclic behaviour and thermal performance. It was found that 0.01 m3 of SIM-3a can provide an average temperature lift of room air, ΔT = 20 °C over 180 min whereas for SIM-3f, ΔT < 15 °C was achieved. Zeolite provided high sorption heat in close approximation with SIM-3a, however, the higher desorption temperature requirements coupled with poor cyclic ability remain as obstacles to the roll out this material commercially. The study results clearly show that the concept of using perforated tubes embedded inside the heat storage material significantly improves performance by enhancing the contact surface area between air → absorbent whilst increasing vapour diffusion. The results suggest a linear correlation between thermal performance and moisture uptake, ΔT–Δw. Determining these operating lines will prove useful for predicting achievable temperature lift and also for effective design and control of thermochemical heat storage systems

An Assessment of Factors Limiting Tropical Congestus Cloud-Top Heights

binding of either tyrosine or 6MPH4 alone does not change the coordination. However, when both tyrosine and 6MPH4 are bound, the active site becomes 5-coordinate, creating an open site for reaction with O2. Investigation of the kinetics of oxygen reactivity of TyrH complexes in the absence and presence of tyrosine and/or 6MPH4 indicated that there is a significant enhancement in reactivity in the 5-coordinate complex in comparison to the 6-coordinate form. Similar investigations with E332A TyrH showed that Glu332 residue plays a role in directing the protonation of the bridged complex that forms prior to the formation of Fe(IV)O. Rapid chemical quench analyses of DOPA formation showed a burst of product formation, suggesting a slow product release step. Steady-state viscosity experiments established a diffusional step as being significantly rate-limiting. Further studies with stopped-flow spectroscopy indicated that the rate of TyrH reaction is determined by a combination of a number of physical and chemical steps. Investigation of the NO complexes of TyrH by means of optical absorption, electron paramagnetic resonance (EPR) and electron spin echo envelope modulation (ESEEM) techniques revealed the relative positions of the substrate and cofactor with respect to NO, an O2 mimic, and provided further insight into how the active site is tuned for catalytic reactivity upon substrate and cofactor binding. The second theory is that a decreased vertical temperature lapse rate, dT/dp, would slow cloud growth, creating a mode of cloud-top heights at the stable layer as clouds lose buoyancy. The signal for lapse rate changes in the AIRS data, however, is not as strong as the signal for RH differences. Near 600-400 hPa, roughly the region where congestus cloud-top heights are located, no significant difference in lapse rates is noted between congestus and deep clouds; in fact, the mean values suggest that congestus clouds appear in more unstable atmospheres than deep clouds. Only slight differences in temperature and lapse rate are noted in ERA data as well. These results suggest that drier air may play a greater role in limiting congestus cloud-top heights than increased atmospheric stability. Five years of relative humidity (RH) observations from the Atmospheric Infrared Sounder (AIRS) instrument aboard the Aqua satellite are then analyzed to identify areas of anomalously dry air between 600 and 400 hPa over deep convective regions of the tropical oceans. Back trajectories are then calculated for each observed parcel

Theoretical analysis of the potential for thermochemical heat storage under Mediterranean climate conditions: Northern Cyprus Case

Thermal energy storage systems are gaining attention in recent years as they are now seen as one of the most promising solutions in order to increase utilisation of solar energy and reduce greenhouse gas emissions. On the other hand in the last decade, thermochemical versions of these systems have been widely researched for ‘seasonal’ storage of solar energy as they have the potential to store heat at ambient temperatures for extended periods of time without any degradation or heat loss. In this study a theoretical analysis of the thermochemical heat storage potential in Mediterranean climate conditions is conducted. A theoretical building located in the northern part of the island of Cyprus is considered as a case study and analysis done using real building data from a site located on the west region (Morphou) of North Cyprus. The analysis results showed that the required heat storage volume to fully compensate heating demand of the building in winter (December to February) is 8 m3 whilst the time required for charging the THS material (Vermiculite-CaCl2) with 8 m2 solar air collectors is slightly more than a month ('i.e.' 35 days during May and June) An analysis of thermochemical heat storage’s economical and greenhouse gas savings compared against gas heaters, electrical heaters and air sourced heat pumps, which are the popular methods for space heating in North Cyprus, is also presented. It was found that payback period of the thermochemical heat storage is 6 years whilst total CO2 emissions savings over 25 years life is 47.9 tonnes

Barriers to recruiting primary care practices for implementation research during COVID-19: A qualitative study of practice coaches from the Stop Unhealthy (STUN) Alcohol Use Now trial

Background: The COVID-19 pandemic has brought widespread change to health care practice and research. With heightened stress in the general population, increased unhealthy alcohol use, and added pressures on primary care practices, comes the need to better understand how we can continue practice-based research and address public health priorities amid the ongoing pandemic. The current study considers barriers and facilitators to conducting such research, especially during the COVID-19 pandemic, within the context of recruiting practices for the STop UNhealthy (STUN) Alcohol Use Now trial. The STUN trial uses practice facilitation to implement screening and interventions for unhealthy alcohol use in primary care practices across the state of North Carolina. Methods: Semistructured interviews were conducted with a purposive sample of 15 practice coaches to discuss their recruitment experiences before and after recruitment was paused due to the pandemic. An inductive thematic analysis was used to identify themes and subthemes. Results: Pandemic-related barriers, including challenges in staffing, finances, and new COVID-19-related workflows, were most prominent. Competing priorities, such as quality improvement measures, North Carolina's implementation of Medicaid managed care, and organizational structures hampered recruitment efforts. Coaches also described barriers specific to the project and to the topic of alcohol. Several facilitators were identified, including the rising importance of behavioral health due to the pandemic, as well as existing relationships between practice coaches and practices. Conclusions: Difficulty managing competing priorities and obstacles within existing practice infrastructure inhibit the ability to participate in practice-based research and implementation of evidence-based practices. Lessons learned from this trial may inform strategies to recruit practices into research and to gain buy-in from practices in adopting evidence-based practices more generally. Plain Language Summary What is known: Unhealthy alcohol use is a significant public health issue, which has been exacerbated during the COVID-19 pandemic. Screening and brief intervention for unhealthy alcohol use is an evidence-based practice shown to help reduce drinking-related behaviors, yet it remains rare in practice. What this study adds: Using a qualitative approach, we identify barriers and facilitators to recruiting primary care practices into a funded trial that uses practice facilitation to address unhealthy alcohol use. We identify general insights as well as those specific to the COVID-19 pandemic. Barriers are primarily related to competing priorities, incentives, and lack of infrastructure. Facilitators are related to framing of the project and the anticipated level and type of resources needed to address unhealthy alcohol use especially as the pandemic wanes. Implications: Our findings provide information on barriers and facilitators to recruiting primary care practices for behavioral health projects and to implementing these activities. Using our findings, we provide a discussion of suggestions for conducting these types of projects in the future which may be of interest to researchers, practice managers, and providers

Numerical and experimental analysis of a novel heat pump driven sorption storage heater

This study investigates a hybrid “solid sorption heat storage/air sourced heat pump” system for energy efficient heating of buildings. The proposed system could convert excess energy generated using photovoltaic panels/off-peak electricity to heat and charge the sorption material to store that heat for later use. The novel heat recovery process employed in the system enables high heat storage efficiency through condensation of desorbed moisture in a heat storage charging cycle. In this study five different sorbents were tested in a novel prototype system. Four sorbents were salt based composites (SIM’s) and one was Zeolite 13X. According to the results, the coefficient of performance (COP) of the system varied in the range of 1–2 for short-term operation (where t < 240 min) depending on the sorption material properties and system operating conditions. The overall performance of the prototype sorption storage heater was determined through long cycle testing. The system provided ≈ 6.8 kWh thermal energy output with a sorbent volume, Vs = 0.04 m3 (over a 1200 min discharge time), corresponding to an energy density, Ed = 170 kWh/m3. The required charging duration, to desorb the moisture was experimentally determined as 360 min. Based on the total energy input–output for both charging and discharging processes, the COPS was calculated at 2.39. According to the analysis, the experimental results were found in good agreement with the numerical simulation

A Neutron Star with a Massive Progenitor in Westerlund 1

We report the discovery of an X-ray pulsar in the young, massive Galactic star cluster Westerlund 1. We detected a coherent signal from the brightest X-ray source in the cluster, CXO J164710.2-455216, during two Chandra observations on 2005 May 22 and June 18. The period of the pulsar is 10.6107(1) s. We place an upper limit to the period derivative of Pdot<2e-10 s/s, which implies that the spin-down luminosity is Edot<3e33 erg/s. The X-ray luminosity of the pulsar is L_X = 3(+10,-2)e33 (D/5 kpc)^2 erg/s, and the spectrum can be described by a kT = 0.61+/-0.02 keV blackbody with a radius of R_bb = 0.27+/-0.03 (D/5 kpc}) km. Deep infrared observations reveal no counterpart with K1 Msun. Taken together, the properties of the pulsar indicate that it is a magnetar. The rarity of slow X-ray pulsars and the position of CXO J164710.2-455216 only 1.6' from the core of Westerlund 1 indicates that it is a member of the cluster with >99.97% confidence. Westerlund 1 contains 07V stars with initial masses M_i=35 Msun and >50 post-main-sequence stars that indicate the cluster is 4+/-1 Myr old. Therefore, the progenitor to this pulsar had an initial mass M_i>40 Msun. This is the most secure result among a handful of observational limits to the masses of the progenitors to neutron stars.Comment: 4 pages, 5 figures. Final version to match ApJL (added one figure since v2

Molecular hydrogen and catalytic combustion in the production of hyperpolarized 83Kr and 129Xe MRI contrast agents

Hyperpolarized (hp) 83Kr is a promising MRI contrast agent for the diagnosis of pulmonary diseases affecting the surface of the respiratory zone. However, the distinct physical properties of 83Kr that enable unique MRI contrast also complicate the production of hp 83Kr. This work presents a radically new approach in the generation of hp 83Kr that can likewise be utilized for the production of hp 129Xe. Molecular nitrogen, typically used as buffer gas in spin exchange optical pumping (SEOP), was replaced by molecular hydrogen without penalty for the achievable hyperpolarization. In this particular study, the highest obtained nuclear spin polarizations were P = 29 % for 83Kr and P = 63 % for 129Xe. The results were reproduced over many SEOP cycles despite the laser induced on-resonance formation of rubidium hydride (RbH). Following SEOP, the H2 was reactively removed via catalytic combustion without measurable losses in hyperpolarized spin state of either 83Kr or 129Xe. Highly spin polarized 83Kr can now be purified for the first time to provide high signal intensity for the advancement of in vivo hp 83Kr MRI. More generally, a chemical reaction appears as a viable alternative to the cryogenic separation process, the primary purification method of hp 129Xe for the past 2 . decades. The inherent simplicity of the combustion process will facilitate hp 129Xe production and should allow for on-demand continuous flow of purified and highly spin polarized 129Xe

Thermal, mechanical and microstructural analysis of concrete containing microencapsulated phase change materials

This paper studies the thermal, mechanical and microstructural aspects of concrete containing different amounts of microencapsulated phase change materials (PCMs). In addition, numerical simulation is carried out to study the potential application of PCM-modified concrete for reduction in summer surface temperature. It is shown that increasing PCM content in concrete led to lower thermal conductivity and an increase in the heat storage ability of concrete. However, the compressive and flexural strength of concrete significantly decreased. Microstructural analysis showed that PCMs appear to remain intact during mixing; however, PCM particles appear to fail by bursting under loading, creating hemispherical voids and crack initiation points as well as possible entrapped air behaviour. The result of numerical simulation revealed that reduction in summer concrete pavement surface temperature by several degrees was possible, with implications for reduction in concrete thermal stresses, shrinkage and urban heat island effect

Floral temperature and optimal foraging: is heat a feasible floral reward for pollinators?

As well as nutritional rewards, some plants also reward ectothermic pollinators with warmth. Bumble bees have some control over their temperature, but have been shown to forage at warmer flowers when given a choice, suggesting that there is some advantage to them of foraging at warm flowers (such as reducing the energy required to raise their body to flight temperature before leaving the flower). We describe a model that considers how a heat reward affects the foraging behaviour in a thermogenic central-place forager (such as a bumble bee). We show that although the pollinator should spend a longer time on individual flowers if they are warm, the increase in total visit time is likely to be small. The pollinator's net rate of energy gain will be increased by landing on warmer flowers. Therefore, if a plant provides a heat reward, it could reduce the amount of nectar it produces, whilst still providing its pollinator with the same net rate of gain. We suggest how heat rewards may link with plant life history strategies