Analysis of Selection of Single or Double U-bend Pipes in a Ground Source Heat Pump System

The ground source heat pump (GSHP) system is widely used because of its energy-saving and environmental-friendly characteristics. The buried pipes heat exchangers play an important role in the whole GSHP system design. However, in most cases, single U-bend pipes are adopted only for their simplicity in design and construction instead of high efficiency and less operation cost of the whole system. In this paper, we make a comparison between single and double U-bend pipe heat exchangers in their heat exchange rate per depth, the number of boreholes needed for the same amount of cooling load, total lengths of pipes for the two different types of heat exchangers, and seasonal overall energy efficiency of the two GSHP systems. An economic analysis method is also presented. Finally, conclusions are made for the selection of single or double U-bend pipe heat exchangers in a GSHP system after a case study using TRNSYS simulation software is carried out

Air Conditioning Cold/Heat Source Analysis of the Inclusion of the Monetary Values of Environmental Damage Based on the LCA Theory

This is an analysis of the effect on the technical solutions when monetary values of externalities are included in a model for selecting air conditioning cold/heat sources. The focus of the study is on heating and cooling using conventional and seawater source heat pump systems. The included monetary values of damage to the environment and health are those result-ing from atmospheric emissions and water-body toxic-ity. An environmental impact assessment model is pre-sented based on the theories of Life Cycle Assessment (LCA) and Willingness - to - pay (WTP). The analysis makes it possible to compare the technical and eco-nomic differences of the air conditioning system based on business economics to a system with greater empha-sis on socio-economics. This model is applied to assess the environmental impacts of two systems. The results show that by considering externality costs, the total discounted cost of the new system would be approxi-mately equal to the conventional one

Study of the design Method of an Efficient Ground Source Heat Pump Thermal Source System in a Cold Area

The ground source heat pump (GSHP) system-an energy efficiency and environment friendly system-is becoming popular in many parts of China. However, an imbalance usually exists between the annual heat extracted from and rejected to the ground due to the different heating and cooling load of a building, which will consistently deteriorate the heat pump efficiency leading even to the breakdown of the heat pump. This paper brings forward a design method of adding supplemental heat rejection equipment, a cooling tower, in the system to solve the problem in a cold area. Taking an office building in Beijing as an example, the authors simulate the GSHP system with two different connection methods between the cooling tower and vertical buried-pipe heat exchangers (in series and in parallel) using TRNSYS simulation software, and put forward several design schemes that can ensure the whole system continually operates with high efficiency. This also makes it possible to perform a more detailed economic optimization of the GSHP-based system in the future

Fetal exposure to bisphenol A as a risk factor for the development of childhood asthma: an animal model study

<p>Abstract</p> <p>Background</p> <p>The prevalence of asthma in industrialized countries has been increasing dramatically and asthma is now the most common chronic disease of children in the United States. The rapidity of the increase strongly suggests that changes in environmental exposures are the likely cause of this epidemic. Further, the early onset of allergic manifestations suggests that these exposures may act on the prenatal development of the immune system. We have focused on the potential effects of bisphenol A (BPA), a chemical pollutant with one of the largest productions, on the development of childhood asthma. We have reported that perinatal BPA exposure promotes the development of allergic asthma in a mouse model. The current study was designed to identify a critical period of BPA exposure and to begin elucidating the mechanisms for this susceptibility.</p> <p>Methods</p> <p>Female BALB/c mice received 10 micro g/ml BPA in their drinking water from one week before pregnancy until the end of the study. Some of the pups were transferred in the first 48 h of life from their BPA-loaded mother to an unexposed mother, or vice versa. Half of the pups were sensitized with a low dose of the experimental allergen ovalbumin (OVA), the rest received PBS as an unsensitized controls. On day 22, the pups were challenged by inhalations of ovalbumin or PBS followed by quantification of eosinophils in and hyperreactivity of their airways, major indicators of experimental asthma in this classical mouse model. Hepatic expression of two isoforms of UDP-glucuronosyltransferase (Ugt) was quantified by quantitative RT-PCR at various ages.</p> <p>Results</p> <p>Pups exposed to BPA in utero and through breast milk, or in utero only, displayed an asthma phenotype in response to their "suboptimal" allergic sensitization, whereas, pups only exposed to BPA postnatally from breast milk, did not. The expression of Ugt2b1, an isoform related to BPA clearance in rats, was not detectable in mouse fetuses and newborn pups, but increased by day 5 and approached adult levels by day 25.</p> <p>Conclusions</p> <p>Prenatal exposures that produce environmentally relevant burdens of BPA, followed by postnatal allergic sensitization and challenges, promote the development of experimental allergic asthma. Delayed expression of BPA-metabolizing enzymes may explain, at least in part, the enhanced fetal susceptibility to this common environmental contaminant.</p

Chinese multinationals: host country factors and foreign direct investment location

The study of Chinese multinationals (MNEs) is becoming one of the most promising research topics in the international business literature. After outlining the distinctive characteristics of the internationalization process of Chinese MNEs, this chapter analyzes the influence of various host country factors on the location of Chinese outward foreign direct investment (FDI). From a sample of 189 outward FDI decisions made by 35 mainland Chinese firms in 63 countries, our results show that host market size and the existence of overseas Chinese in the host country are positively associated with the number of Chinese FDIs. However, greater difficulty in doing business and host country political risk have no effect

Dynamics of generalized PT-symmetric dimers with time-periodic gain–loss

A parity-time (PT)-symmetric system with periodically varying-in-time gain and loss modeled by two coupled Schrödinger equations (dimer) is studied. It is shown that the problem can be reduced to a perturbed pendulum-like equation. This is done by finding two constants of motion. Firstly, a generalized problem using Melnikov-type analysis and topological degree arguments is studied for showing the existence of periodic (libration), shift- periodic (rotation), and chaotic solutions. Then these general results are applied to the PT-symmetric dimer. It is interestingly shown that if a sufficient condition is satisfied, then rotation modes, which do not exist in the dimer with constant gain–loss, will persist. An approximate threshold for PT-broken phase corresponding to the disappearance of bounded solutions is also presented. Numerical study is presented accompanying the analytical results

A retrospective and agenda for future research on Chinese outward foreign direct investment

Our original paper “The determinants of Chinese Outward Foreign Direct Investment” was the first theoretically based empirical analysis of the phenomenon. It utilised internalisation theory to show that Chinese state-owned firms reacted to home country market imperfections to surmount barriers to foreign entry arising from naivety and the lack of obvious ownership advantages, leveraging institutional factors including favourable policy stimuli. This special theory explained outward foreign direct investment (OFDI) but provided surprises. These included the apparent appetite for risk evinced by these early investors, causing us to conjecture that domestic market imperfections, particularly in the domestic capital market, might be responsible. The article stimulated a massive subsequent, largely successful, research effort on emerging country multinationals. In this Retrospective article we review some of the main strands of research that ensued, for the insight they offer for the theme of our commentary. Our theme is that theoretical development can only come through embracing yet more challenging, different, and new contexts, and we make suggestions for future research directions

Marine algae and land plants share conserved phytochrome signaling systems

Phytochrome photosensors control a vast gene network in streptophyte plants, acting as master regulators of diverse growth and developmental processes throughout the life cycle. In contrast with their absence in known chlorophyte algal genomes and most sequenced prasinophyte algal genomes, a phytochrome is found in Micromonas pusilla , a widely distributed marine picoprasinophyte (<2 μm cell diameter). Together with phytochromes identified from other prasinophyte lineages, we establish that prasinophyte and streptophyte phytochromes share core lightinput and signaling-output domain architectures except for the loss of C-terminal response regulator receiver domains in the streptophyte phytochrome lineage. Phylogenetic reconstructions robustly support the presence of phytochrome in the common progenitor of green algae and land plants. These analyses reveal a monophyletic clade containing streptophyte, prasinophyte, cryptophyte, and glaucophyte phytochromes implying an origin in the eukaryotic ancestor of the Archaeplastida. Transcriptomic measurements reveal diurnal regulation of phytochrome and bilin chromophore biosynthetic genes in Micromonas. Expression of these genes precedes both light-mediated phytochrome redistribution from the cytoplasm to the nucleus and increased expression of photo-synthesis-associated genes. Prasinophyte phytochromes perceive wavelengths of light transmitted farther through seawater than the red/far-red light sensed by land plant phytochromes. Prasinophyte phytochromes also retain light-regulated histidine kinase activity lost in the streptophyte phytochrome lineage. Our studies demonstrate that light-mediated nuclear translocation of phytochrome predates the emergence of land plants and likely represents a widespread signaling mechanism in unicellular algae