Experimental Research On Gas Injection High Temperature Heat Pump With An Economizer

Gas injection technology is often used in cold regions to solve heat pump’s low heating capacity and high discharge temperature at low ambient temperature. Injecting gas into port opened at specific position of compressor could increase mass flow rate of compressor and total heating capacity of heat pump. Gas injection also changes compression ratio of compressor and decreases discharge temperature. An optimal gas injection pressure is got when the coefficient of performance reached to peak value at a certain working condition. It’s a feasible way to increase performance of heat pump at cold regions. High temperature heat pump could provide higher temperature water for industrial usage regions but there still existed some problems on its usage. Total heating capacity decreased and discharge temperature increased with the raise of condensation temperature. Refrigerant temperature before throttling valve was high and may exceed working temperature range of electrical expansion valve. Gas injection technology with an economizer was adopted to solve these problems. A new high temperature heat pump cycle was designed based on gas injection and outlets water temperature of the prototype manufactured was reached to 90?. Temperature before throttling valve was well controlled by the usage of economizer. Heating capacity, discharge temperature, compressor power consumption of the heat pump system at different amount of injected gas was conducted by theoretical and experimental research in this paper. This study showed the function of gas injection technology which used in high temperature heat pump

Optimal operation of compressors in an integrated gas and electricity system-an enhanced MISOCP method

The optimal operation of gas-driven compressors (GDCs) and electric-driven compressors (EDCs) was investigated to minimise the cost of operating a gas network. The operational optimisation model of the gas network with relatively detailed representation of gas compressors was formulated as a Mixed-Integer Second Order Cone Programming (MISOCP) problem. A bound-tightening algorithm was used to improve the quality of the solution from the relaxed MISOCP formulation. Using this model, the operation of the high-pressure gas transmission network in South Wales and Southwest of England was optimised considering day-ahead gas and electricity prices. The results show that, compared to the case in which only gas-driven compressors are available, nearly 63% of the operating cost of the gas network can be reduced through coordinated operation of gas-driven and electric-driven compressors, while it produces only 36% of carbon dioxide emissions compared of case that only gas-driven compressors are allowed to work. Although, these specific figures for cost and emission reductions depend on electricity and gas prices, as well as emission intensity of the power grid, the results demonstrate the potential for using the inherent flexibility of the high pressure gas network to reduce its operating cost and emission, and to support the operation of power systems. The within-pipe storage capability (i.e., linepack) of the high-pressure gas network is a key enabler that allows electric-driven compressors to shift their operation schedule in time to benefit from low electricity prices

Preparation of terminal blend/ grafting activated crumb rubber composite modified asphalt based on response surface methodology

Recycling waste tires, crushing them into crumb rubber (CR) and adding them to asphalt can effectively improve the performance and prolong the service life of asphalt pavement. However, the crumb rubber modified asphalt (CRMA) prepared by aforementioned process is prone to segregation during storage and transportation. The terminal blend rubber asphalt (TB) prepared with fine rubber powder by high-speed shearing at high temperature for long time, which effectively improves the storage stability and working performance of crumb rubber modified asphalt, but reduces the high-temperature performance. In this study, grafting activated crumb rubber (GACR) was incorporated into TB to improve its high temperature performance without impairing storage stability. Using shearing temperature, shearing time and grafting activated crumb rubber content as influencing factors, the response surface method (RSM) was carried out to optimize the preparation process. The results indicated that 180°C was a critical temperature, and the swelling of crumb rubber dominated with the temperature below it, but the desulfurization prevailed with the temperature above it. The extension of time favored the swelling of crumb rubber at low temperature but promoted desulfurization at high temperature. With the increase of crumb rubber content, the high temperature performance of modified asphalt improved whereas the storage stability deteriorated. According to the determination of response values and the prediction of optimal values, the suitable preparation conditions and parameters were recommended as shearing temperature of 190°C, shearing time of 90 min, and GACR content of 15%. The composite modified asphalt prepared through the optimized process showed good high temperature stability and storage stability

Stress CMR T1-mapping technique for assessment of coronary microvascular dysfunction in a rabbit model of type II diabetes mellitus: Validation against histopathologic changes

BackgroundCoronary microvascular dysfunction (CMD) is an early character of type 2 diabetes mellitus (T2DM), and is indicative of adverse events. The present study aimed to validate the performance of the stress T1 mapping technique on cardiac magnetic resonance (CMR) for identifying CMD from a histopathologic perspective and to establish the time course of CMD-related parameters in a rabbit model of T2DM.MethodsNew Zealand white rabbits (n = 30) were randomly divided into a control (n = 8), T2DM 5-week (n = 6), T2DM 10-week (n = 9), and T2DM 15-week (n = 7) groups. The CMR protocol included rest and adenosine triphosphate (ATP) stress T1-mapping imaging using the 5b(20b)3b-modified look-locker inversion-recovery (MOLLI) schema to quantify stress T1 response (stress ΔT1), and first-pass perfusion CMR to quantify myocardial perfusion reserve index (MPRI). After the CMR imaging, myocardial tissue was subjected to hematoxylin-eosin staining to evaluate pathological changes, Masson trichrome staining to measure collagen volume fraction (CVF), and CD31 staining to measure microvascular density (MVD). The associations between CMR parameters and pathological findings were determined using Pearson correlation analysis.ResultsThe stress ΔT1 values were 6.21 ± 0.59%, 4.88 ± 0.49%, 3.80 ± 0.40%, and 3.06 ± 0.54% in the control, T2DM 5-week, 10-week, and 15-week groups, respectively (p < 0.001) and were progressively weakened with longer duration of T2DM. Furthermore, a significant correlation was demonstrated between the stress ΔT1 vs. CVF and MVD (r = −0.562 and 0.886, respectively; p < 0.001).ConclusionThe stress T1 response correlated well with the histopathologic measures in T2DM rabbits, indicating that it may serve as a sensitive CMD-related indicator in early T2DM

Selection of Anti-Sulfadimidine Specific ScFvs from a Hybridoma Cell by Eukaryotic Ribosome Display

BACKGROUND:Ribosome display technology has provided an alternative platform technology for the development of novel low-cost antibody based on evaluating antibiotics derived residues in food matrixes. METHODOLOGY/PRINCIPAL FINDINGS:In our current studies, the single chain variable fragments (scFvs) were selected from hybridoma cell lines against sulfadimidine (SM(2)) by using a ribosome library technology. A DNA library of scFv antibody fragments was constructed for ribosome display, and then mRNA-ribosome-antibody (MRA) complexes were produced by a rabbit reticulocyte lysate system. The synthetic sulfadimidine-ovalbumin (SM(2)-OVA) was used as an antigen to pan MRA complexes and putative scFv-encoding genes were recovered by RT-PCR in situ following each panning. After four rounds of ribosome display, the expression vector pCANTAB5E containing the selected specific scFv DNA was constructed and transformed into Escherichia coli HB2151. Three positive clones (SAS14, SAS68 and SAS71) were screened from 100 clones and had higher antibody activity and specificity to SM(2) by indirect ELISA. The three specific soluble scFvs were identified to be the same molecular weight (approximately 30 kDa) by Western-blotting analysis using anti-E tag antibodies, but they had different amino acids sequence by sequence analysis. CONCLUSIONS/SIGNIFICANCE:The selection of anti-SM(2) specific scFv by in vitro ribosome display technology will have an important significance for the development of novel immunodetection strategies for residual veterinary drugs