Enhancement of R1234ze(Z) Pool Boiling Heat Transfer on Horizontal Titanium Tubes for High Temperature Heat Pumps

Low GWP refrigerant R1234ze(Z) is promising candidate of refrigerant used in industrial high temperature heat pumps. The heat exchangers of such heat pumps designed for waste heat recovery systems is exposed to the exhaust containing acid substances. Using titanium as the material can be one solution to prevent oxidation. In this study, pool boiling heat transfer characteristics outside of horizontal titanium tubes were experimentally investigated for R1234ze(Z) at relatively higher temperatures. A plain tube and three enhanced tubes having different fin geometry were tested in a pressure vessel and the bubble behavior was observed. The experiment covers saturation temperatures from 10 to 60 °C and heat fluxes from 0.55 to 79.8 kWm-2. With the plain tube, it was confirmed that the measured heat transfer coefficients on the plain tube agree with the calculated heat transfer coefficients by Jung et al. correlation proposed for other HFC refrigerants within ±15%. The notable difference to the typical material copper is thermal resistance over the tube wall. Because the thermal conductivity of titanium is only 19 W m-1K-1 (that of copper is approximately 360 W m-1K-1), the thermal resistance is onsiderable. Comparing to the plain tube, the tested enhanced tube exhibited 2.8 to 5.1 times higher heat transfer coefficient, on average, in the test range. This could compensate the disadvantage in thermal conductivity for titanium. The enhancement ratio predominantly depends on the saturation temperature and wall heat flux. At conditions of the higher saturation temperatures and lower heat fluxes, where smaller bubbles were observed, the test tube having smaller fin spaces exhibits higher heat transfer coefficient. The experimental results remark the importance of fin geometry optimization to the operation conditions

Comparison on Evaporation Heat Transfer between R32/R1234yf and R32/R1234ze(E) Flowing in Horizontal Microfin Tubes

Refrigerant mixtures R32/R1234yf and R32/R1234ze(E) are considered to be the low GWP alternatives of R32 and R410A for air conditioners. However, according to the recent reports, the severe heat transfer degradation is encountered during the evaporation process. This implies that much larger heat exchangers are required to maintain the COP and cooling/heating capacity with R32/R1234yf and R32/R1234ze(E). Therefore, the effects of mixture component and composition on the heat transfer degradation is experimentally investigated in this paper. Heat transfer coefficient of those two mixtures and their components (i.e., R32, R1234yf and R1234ze(E) alone) are experimentally quantified with horizontally set copper microfin tubes of 6.00 mm in outer diameter having 48, 58, and 64 fins of 0.26 mm in height and 19 ° in helical angle. The evaporation test was conducted at an average saturation temperature of 10 °C, a heat flux of 10 kW m-2, and mass fluxes from 150 to 400 kg m-2s-1. The heat transfer is degraded most at the composition where the temperature glide and concentration difference between vapor and liquid phases are maximized. This suggest that the relevance of the heat transfer degradation and mass transfer resistance caused by the concentration boundary layer and the additional sensible heat transfer. Although the heat transfer coefficients of R1234yf and R1234ze(E) alone are comparable, the magnitude of heat transfer degradation is obviously severer for R32/R1234ze(E) than that for R R32/R1234yf. This can be explained with the larger concentration difference and the temperature glide of R32/R1234ze(E) that those of R32/R1234yf. With increasing mass flux and number of fins, the heat transfer degradation is mitigated somewhat. It appears to be that mixing of concentration boundary layer contributes to recover the evaporation heat transfer. For the real possibility to use R32/R1234yf and R32/R1234ze(E) in air conditioners, the heat transfer recovery or enhancement could be the key technology

Performance Evaluation of Heat Pump Cycle using Low GWP Refrigerant Mixtures of HFC-32 and HFO-1123

Hydro-fluorocarbons (HFCs) have been widely used as working fluids (refrigerants) in air-conditioning and refrigeration systems. At the 1997 Kyoto Conference (COP3), a worldwide agreement was obtained to regulate the production and use of HFCs exhibit high global warming potential (GWP). In the above situation, Hydro-fluoro Olefins (HFOs) having extremely low GWP values such as HFO-1234yf, HFO-1234ze(E), HFO-1123, has attracted attentions. In this study, the performance of heat pump cycle using low GWP refrigerant mixtures of HFC-32 and HFO-1123 is evaluated experimentally. The experimental system is a water heat source vapor compression cycle, mainly composed of an inverter-controlled & hermetic-type scroll compressor (cylinder volume: 11 cm3), an oil separator, a double-tube-type condenser (heat transfer tube; inner grooved , OD 9.53 mm, ID 7.53 mm, total length 7.2 m), a liquid receiver, a solenoid expansion valve, and a double-tube-type evaporator (heat transfer tube; inner grooved , OD 9.53 mm, ID 7.53 mm, total length 7.2 m). Tested compositions of mixtures of HFO-32/HFO-1123 are 58/42 mass% (GWP=393) and 42/58 mass% (GWP=285). These mixtures are tested for the heating and the cooling modes. In the heating mode, the heat sink water temperatures at the inlet and outlet of condenser are kept at 20 ˚C and 45 ˚C, respectively, and the heat source water temperatures at the inlet and outlet of evaporator are kept at 15 ˚C and 9 ˚C. Then, the heating load is varied from 1.6 kW to 2.6 kW. Similarly, in the cooling mode, the water temperature at the inlet and outlet are kept at 30 ˚C and 45 ˚C in condenser, and at 20 ˚C and 10 ˚C in evaporator. Then, the cooling load is varied from 1.4 kW to 2.4 kW. The conventional refrigerant R410A is also tested as the reference. In both modes of heating and cooling, the COP of HFO-32/HFO-1123 mixture (58/42 mass%) is almost the same as that of R410A, while the COP of HFO-32/HFO-1123 mixture (42/58 mass%) is a little lower than that of R410A. By analyzing the irreversible loss of the heat pump cycle based on the second low analysis, the losses of both mixtures in condenser and evaporator are slightly smaller than that of R410A, while the losses of both mixtures in compressor are slightly higher than that of R410A. This result reveals that tested mixtures of HFO-32/HFO-1123 are available to use as the alternative of R410A if the design of compressor and heat exchangers are optimized

Experimental Assessment on Performance of a Heat Pump Cycle Using R32/R1234yf and R744/R32/R1234yf

     Hydro-fluorocarbons (HFCs) are widely used as working fluids (refrigerants) in air-conditioning and refrigeration systems. However, at the 1997 Kyoto Conference (COP3), it was determined that the product and use of HFCs should be regulated due to their high global warming potential (GWP). In the above mentioned situation for the air-conditioning and refrigeration systems, recently, R1234yf having extremely low-GWP was nominated as one of the alternates of HFCs. Some literatures reported that the heating capacity of heat pump cycles using R1234yf is less than R410A because of its smaller vapor density and latent heat. To achieve the performance comparable to R410A, much larger unit is required. Therefore, in this present study, mixing with R32 of larger latent heat and relatively low-GWP into R1234yf was attempted. Additionally, R744 having higher vapor density and extremely low-GWP was added into R32/R1234yf.  The R32/R1234yf and R744/R32/R1234yf are zeotropic mixtures that cause temperature change during the phase-change, typically called temperature glide. When this temperature glide is utilized effectively to decrease the irreversible loss in heat exchanger, the cycle performance can be improved. The degree of temperature glide is determined by the composition of refrigerant mixtures. The composition of the test refrigerants are selected from the criterions of GWPs just below 300 and 200.Experiment was conducted with a vapor compression heat pump cycle using a compressor developed for R410A. The condenser and the evaporator are tube-in tube heat exchangers of counter-flow configuration.  At compositions with GWP200 and a given heating capacity, the COP of R32/R1234yf and R744/R32/R1234yf are lower than that of R410A. The main causes were that R32/R1234yf of GWP200 has lower vapor density and R744/R32/R1234yf of GWP200 has lager temperature glide. At compositions with GWP300, R32/R1234yf and R744/R32/R1234yf exhibit comparable COP and heating capacity to R410A. Using R32/R1234yf and R744/R32/R1234yf of compositions with GWP300, as the alternatives of R410A, is feasible idea

Intracorporeal semi‐hand‐sewn Billroth I reconstruction in total laparoscopic distal gastrectomy

Introduction Intracorporeal Billroth I (B‐I) reconstruction using an endoscopic linear stapler (ELS) is widely performed in total laparoscopic distal gastrectomy. However, conventional procedures require many ELSs for anastomosis. Here, we introduce the novel intracorporeal semi‐hand‐sewn (SHS) B‐I reconstruction. Materials and surgical technique After the transection of stomach and duodenum using ELS following adequate lymph node dissection, small entry holes were made on the anterior wall in the greater curvature of the stomach and the duodenal stump. The posterior walls of both the remnant stomach and the duodenum were attached with the ELS and fired to create the posterior wall of the B‐I anastomosis. All the transection line of the duodenum and one‐third of the transection line of the stomach were dissected; finally the anterior wall suturing at the anastomotic site was performed by the laparoscopic hand‐sewn technique. Discussion SHS procedure was performed for 17 gastric cancer patients. There were no intraoperative complications or conversions to open surgery. One intra‐abdominal abscess was observed although there was no anastomotic leakage. The median reconstruction time was 48 minutes (32‐63). The SHS procedure was safe, feasible, and economical, although it requires sufficient laparoscopic suturing and ligation skill

Short-term and long-term comparisons of laparoscopy-assisted proximal gastrectomy with esophagogastrostomy by the double-flap technique and laparoscopy-assisted total gastrectomy for proximal gastric cancer

Background Although proximal gastrectomy (PG) is a recognized surgical procedure for early proximal gastric cancer, total gastrectomy (TG) is sometimes selected due to concern about severe gastroesophageal reflux. Esophagogastrostomy by the double-flap technique (DFT) is an anti-reflux reconstruction after PG, and its short-term effectiveness has been reported. However, little is known about the long-term effects on nutritional status and quality of life (QOL). Methods Gastric cancer patients who underwent laparoscopy-assisted PG (LAPG) with DFT or laparoscopy-assisted TG (LATG) between April 2011 and March 2014 were retrospectively analyzed. Body weight (BW), body mass index (BMI), and prognostic nutritional index (PNI) were reviewed to assess nutritional status, and the Postgastrectomy Syndrome Assessment Scale (PGSAS)-45 was used to assess QOL. Results A total of 36 patients (LATG: 17, LAPG: 19) were enrolled. Four of 17 LATG patients (24%) were diagnosed with Stage ≥II after surgery, and half received S-1 adjuvant chemotherapy. BW and PNI were better maintained in LAPG than in LATG patients until 1-year follow-up. Seven of 16 LATG patients (44%) were categorized as “underweight (BMI Conclusions LAPG with DFT was superior to LATG in postoperative nutritional maintenance, and can be the first option for early proximal gastric cancer

Genetic cholesteryl ester transfer protein deficiency caused by two prevalent mutations as a major determinant of increased levels of high density lipoprotein cholesterol

金沢大学大学院医学系研究科病態検査学Genetic determinants of HDL cholesterol (HDL-C) levels in the general population are poorly understood. We previously described plasma cholesteryl ester transfer protein (CETP) deficiency due to an intron 14 G(+1)-to-A mutation(Int14 A) in several families with very high HDL-C levels in Japan. Subjects with HDL-C ≥ 100 mg/dl (n = 130) were screened by PCR single strand conformational polymorphism analysis of the CETP gene. Two other mutations were identified by DNA sequencing or primer-mediated restriction map modification of PCR products: a novel intron 14 splice donor site mutation caused by a T insertion at position +3 from the exon14/intron14 boundary (Int14 T) and a missense mutation (Asp442 to Gly) within exon 15 (D442G). The Int14 T mutation was only found in one family. However, the D442G and Int14 A mutations were highly prevalent in subjects with HDL-C ≥ 60 mg/dl, with combined allele frequencies of 9%, 12%, 21%, and 43% for HDL-C 60-79, 80-99, 100-119, and ≥ 120 mg/dl, respectively. Furthermore, prevalences of the D442G and Int14 A mutations were extremely high in a general sample of Japanese men (n = 236), with heterozygote frequencies of 7% and 2%, respectively. These two mutations accounted for about 10% of the total variance of HDL-C in this population. The phenotype in a genetic compound heterozygote (Int14 T and Int14 A) was similar to that of Int14 A homozygotes (no detectable CETP and markedly increased HDL-C), indicating that the Int14 T produces a null allele. In four D442G homozygotes, mean HDL-C levels (86±26 mg/dl) were lower than in Int14 A homozygotes (158±35 mg/dl), reflecting residual CETP activity in plasma. In 47 D442G heterozygotes, mean HDL-C levels were 91±23 mg/dl, similar to the level in D442G homozygotes, and significantly greater than mean HDL-C levels in Int14 A heterozygotes (69±15 mg/dl). Thus, the D442G mutation acts differently to the null mutations with weaker effects on HDL in the homozygous state and stronger effects in the heterozygotes, suggesting dominant expression of a partially defective allele. CETP deficiency, reflecting two prevalent mutations (D442G and Int14 A), is the first example of a genetic deficiency state which is sufficiently common to explain a significant fraction of the variation in HDL-C in the general population

First Data Release of the Hyper Suprime-Cam Subaru Strategic Program

The Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) is a three-layered imaging survey aimed at addressing some of the most outstanding questions in astronomy today, including the nature of dark matter and dark energy. The survey has been awarded 300 nights of observing time at the Subaru Telescope and it started in March 2014. This paper presents the first public data release of HSC-SSP. This release includes data taken in the first 1.7 years of observations (61.5 nights) and each of the Wide, Deep, and UltraDeep layers covers about 108, 26, and 4 square degrees down to depths of i~26.4, ~26.5, and ~27.0 mag, respectively (5sigma for point sources). All the layers are observed in five broad bands (grizy), and the Deep and UltraDeep layers are observed in narrow bands as well. We achieve an impressive image quality of 0.6 arcsec in the i-band in the Wide layer. We show that we achieve 1-2 per cent PSF photometry (rms) both internally and externally (against Pan-STARRS1), and ~10 mas and 40 mas internal and external astrometric accuracy, respectively. Both the calibrated images and catalogs are made available to the community through dedicated user interfaces and database servers. In addition to the pipeline products, we also provide value-added products such as photometric redshifts and a collection of public spectroscopic redshifts. Detailed descriptions of all the data can be found online. The data release website is https://hsc-release.mtk.nao.ac.jp/.Comment: 34 pages, 20 figures, 7 tables, moderate revision, accepted for publication in PAS

Dietary patterns associated with fall-related fracture in elderly Japanese: a population based prospective study

<p>Abstract</p> <p>Background</p> <p>Diet is considered an important factor for bone health, but is composed of a wide variety of foods containing complex combinations of nutrients. Therefore we investigated the relationship between dietary patterns and fall-related fractures in the elderly.</p> <p>Methods</p> <p>We designed a population-based prospective survey of 1178 elderly people in Japan in 2002. Dietary intake was assessed with a 75-item food frequency questionnaire (FFQ), from which dietary patterns were created by factor analysis from 27 food groups. The frequency of fall-related fracture was investigated based on insurance claim records from 2002 until 2006. The relationship between the incidence of fall-related fracture and modifiable factors, including dietary patterns, were examined. The Cox proportional hazards regression model was used to examine the relationships between dietary patterns and incidence of fall-related fracture with adjustment for age, gender, Body Mass Index (BMI) and energy intake.</p> <p>Results</p> <p>Among 877 participants who agreed to a 4 year follow-up, 28 suffered from a fall-related fracture. Three dietary patterns were identified: mainly vegetable, mainly meat and mainly traditional Japanese. The moderately confirmed (see statistical methods) groups with a Meat pattern showed a reduced risk of fall-related fracture (Hazard ratio = 0.36, 95% CI = 0.13 - 0.94) after adjustment for age, gender, BMI and energy intake. The Vegetable pattern showed a significant risk increase (Hazard ratio = 2.67, 95% CI = 1.03 - 6.90) after adjustment for age, gender and BMI. The Traditional Japanese pattern had no relationship to the risk of fall-related fracture.</p> <p>Conclusions</p> <p>The results of this study have the potential to reduce fall-related fracture risk in elderly Japanese. The results should be interpreted in light of the overall low meat intake of the Japanese population.</p