Effects of vapor injection modes on the heating performance of heat pumps

2019 ◽  
Vol 86 (3) ◽  
pp. 30902 ◽  
Author(s):  
Bin Liu ◽  
Lin Chai ◽  
Aiqiang Chen ◽  
Fuhui Tang ◽  
Khellil Sefiane ◽  
...  
Keyword(s):  
Heat Pump ◽  
Heat Pumps ◽  
Two Stage ◽  
Heating Efficiency ◽  
One Stage ◽  
Vapor Injection ◽  
Heating Capacity ◽  
Attenuation Rate ◽  
Wide Range ◽  
The One

Heat pumps are widely investigated for their versatile use in a wide range of applications. In this study, three types of heat pumps were experimentally compared. These heat pumps include an one-stage without injection vapor heat pump, an one-stage injection vapor heat hump and a two-stage injection vapor heat pump with an economizer. The results showed that the heating capacity of all three variants of heat pumps decreases with the decrease of the evaporation temperature. However, the attenuation ratio of the heating capacity is found to be different from one pump to another. On the one hand, the largest attenuation rate is found to be 68.84% for evaporating temperatures ranging from −1 °C to −23 °C and for the case of one-stage heat pump. On the other hand, the smallest attenuation rate is found to be 31% for the two-stage injection vapor heat pump in the same temperature range. It is worth noting that the heating efficiency is improved by the amount of vapor injection, nevertheless, there is a maximum value due to the limitations of the economizer. The two-stage injection vapor heat pump can exhibit an enhanced heating efficiency of 127% compared to the one-stage without injection vapor heat pump and 13% compared to the one-stage injection vapor heat pump for an evaporating temperature of −23 °C.

Two-Stage Procedure for the Quantitative Determination of Autoprothrombin III Concentration and Some Applications

1967 ◽  
Vol 18 (01/02) ◽  
pp. 198-210 ◽  
Author(s):  
Ronald S Reno ◽  
Walter H Seegers
Keyword(s):  
Prothrombin Time ◽  
Factor Vii ◽  
Two Stage ◽  
Pronounced Increase ◽  
One Stage ◽  
Assay Procedure ◽  
Bovine Plasma ◽  
The One ◽  
Autoprothrombin C

SummaryA two-stage assay procedure was developed for the determination of the autoprothrombin C titre which can be developed from prothrombin or autoprothrombin III containing solutions. The proenzyme is activated by Russell’s viper venom and the autoprothrombin C activity that appears is measured by its ability to shorten the partial thromboplastin time of bovine plasma.Using the assay, the autoprothrombin C titre was determined in the plasma of several species, as well as the percentage of it remaining in the serum from blood clotted in glass test tubes. Much autoprothrombin III remains in human serum. With sufficient thromboplastin it was completely utilized. Plasma from selected patients with coagulation disorders was assayed and only Stuart plasma was abnormal. In so-called factor VII, IX, and P.T.A. deficiency the autoprothrombin C titre and thrombin titre that could be developed was normal. In one case (prethrombin irregularity) practically no thrombin titre developed but the amount of autoprothrombin C which generated was in the normal range.Dogs were treated with Dicumarol and the autoprothrombin C titre that could be developed from their plasmas decreased until only traces could be detected. This coincided with a lowering of the thrombin titre that could be developed and a prolongation of the one-stage prothrombin time. While the Dicumarol was acting, the dogs were given an infusion of purified bovine prothrombin and the levels of autoprothrombin C, thrombin and one-stage prothrombin time were followed for several hours. The tests became normal immediately after the infusion and then went back to preinfusion levels over a period of 24 hrs.In other dogs the effect of Dicumarol was reversed by giving vitamin K1 intravenously. The effect of the vitamin was noticed as early as 20 min after administration.In response to vitamin K the most pronounced increase was with that portion of the prothrombin molecule which yields thrombin. The proportion of that protein with respect to the precursor of autoprothrombin C increased during the first hour and then started to go down and after 3 hrs was equal to the proportion normally found in plasma.

Standardization of Factor VIII – IV. Establishment of the 3rd International Standard for Factor VIII: C Concentrate

1983 ◽  
Vol 50 (03) ◽  
pp. 697-702 ◽  
Author(s):  
T W Barrowcliffe ◽  
A D Curtis ◽  
D P Thomas
Keyword(s):  
Factor Viii ◽  
High Purity ◽  
Collaborative Study ◽  
World Health ◽  
Current Standard ◽  
Two Stage ◽  
International Standard ◽  
One Stage ◽  
The One ◽  
Health Organization

SummaryAn international collaborative study was carried out to establish a replacement for the current (2nd) international standard for Factor VIII: C, concentrate. Twenty-six laboratories took part, of which 17 performed one-stage assays, three performed two-stage assays and six used both methods. The proposed new standard, an intermediate purity concentrate, was assayed against the current standard, against a high-purity concentrate and against an International Reference Plasma, coded 80/511, previously calibrated against fresh normal plasma.Assays of the proposed new standard against the current standard gave a mean potency of 3.89 iu/ampoule, with good agreement between laboratories and between one-stage and two- stage assays. There was also no difference between assay methods in the comparison of high-purity and intermediate purity concentrates. In the comparison of the proposed standard with the plasma reference preparation, the overall mean potency was 4.03 iu/ampoule, but there were substantial differences between laboratories, and the two-stage method gave significantly higher results than the one stage method. Of the technical variables in the one-stage method, only the activation time with one reagent appeared to have any influence on the results of this comparison of concentrate against plasma.Accelerated degradation studies showed that the proposed standard is very stable. With the agreement of the participants, the material, in ampoules coded 80/556, has been established by the World Health Organization as the 3rd International Standard for Factor VIII :C, Concentrate, with an assigned potency of 3.9 iu/ampoule.

scholarly journals Study on the Leakage and Inter-Stage Pressure Drop Characteristics of Two-Stage Finger Seal

2021 ◽  
Vol 11 (5) ◽  
pp. 2239
Author(s):  
Hailin Zhao ◽  
Hua Su ◽  
Guoding Chen ◽  
Yanchao Zhang
Keyword(s):  
Pressure Drop ◽  
Pressure Difference ◽  
Radial Displacement ◽  
Mean Square ◽  
The Finite Element Method ◽  
Axial Pressure ◽  
Two Stage ◽  
One Stage ◽  
The One ◽  
Lower Contact

To solve the high leakage and high wear problems faced by sealing devices in aeroengines under the condition of high axial pressure difference, the two-stage finger seal is proposed in this paper. The finite element method and computational fluid dynamics (FEM/CFD) coupling iterative algorithm of the two-stage finger seal is developed and validated. Then the performance advantages of two-stage finger seal compared to the one-stage finger seal are studied, as well as the leakage and the inter-stage pressure drop characteristics of two-stage finger seal are investigated. Finally, the measure to improve the inter-stage imbalance of pressure drop of two-stage finger seal is proposed. The results show that the two-stage finger seal has lower leakage and lower contact pressure than the one-stage finger seal at high axial pressure difference, but there exists an inter-stage imbalance of pressure drop. Increasing the axial pressure difference and the root mean square (RMS) roughness of finger element can aggravate the imbalance of pressure drop, while the radial displacement excitation of rotor has little influence on it. The results also indicate that the inter-stage imbalance of pressure drop of the two-stage finger seal can be improved by increasing the number of finger elements of the 1st finger seal and decreasing the number of finger elements of the 2nd finger seal.

scholarly journals Performance Analysis of High-temperature Two-stage Compression Heat Pump with Vapor Injection Dynamic Control

2020 ◽  
Vol 32 (12) ◽  
pp. 4259
Author(s):  
Win-Jet Luo ◽  
Jin-Chang Lai ◽  
Ming-Chu Hsieh ◽  
I-Hsing Huang
Keyword(s):  
High Temperature ◽  
Performance Analysis ◽  
Heat Pump ◽  
Dynamic Control ◽  
Two Stage ◽  
Vapor Injection

scholarly journals Object Detection in Very High-Resolution Aerial Images Using One-Stage Densely Connected Feature Pyramid Network

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3341 ◽  
Author(s):  
Hilal Tayara ◽  
Kil Chong
Keyword(s):  
High Resolution ◽  
Object Detection ◽  
Computation Time ◽  
Aerial Images ◽  
Feature Maps ◽  
Two Stage ◽  
One Stage ◽  
Wide Range ◽  
Feature Pyramid ◽  
Very High

Object detection in very high-resolution (VHR) aerial images is an essential step for a wide range of applications such as military applications, urban planning, and environmental management. Still, it is a challenging task due to the different scales and appearances of the objects. On the other hand, object detection task in VHR aerial images has improved remarkably in recent years due to the achieved advances in convolution neural networks (CNN). Most of the proposed methods depend on a two-stage approach, namely: a region proposal stage and a classification stage such as Faster R-CNN. Even though two-stage approaches outperform the traditional methods, their optimization is not easy and they are not suitable for real-time applications. In this paper, a uniform one-stage model for object detection in VHR aerial images has been proposed. In order to tackle the challenge of different scales, a densely connected feature pyramid network has been proposed by which high-level multi-scale semantic feature maps with high-quality information are prepared for object detection. This work has been evaluated on two publicly available datasets and outperformed the current state-of-the-art results on both in terms of mean average precision (mAP) and computation time.

scholarly journals Identification of Sources of Inter-Laboratory Variation in Factor VIII Assay

1977 ◽  
Author(s):  
T.B.L. Kirkwood ◽  
C.R. Rizza ◽  
T.J. Snape ◽  
I. Rhymes ◽  
D.E.G. Austen
Keyword(s):  
Factor Viii ◽  
Systematic Difference ◽  
Normal System ◽  
Two Stage ◽  
Initial Dilution ◽  
One Stage ◽  
Collaborative Studies ◽  
Freeze Dried ◽  
Sources Of Variation ◽  
The One

A repeated finding of national and international collaborative studies of standard Factor VIII preparations has been that systematic differences exist between laboratories in their measurement of the relative activities of the same pairs of Factor VIII preparations.A workshop meeting was held at the Oxford Haemophilia Centre (England) during 23rd-26th November 1976 to investigate which of the possible sources of variation between laboratories were responsible. Participants from 16 British laboratories (9 one-stage, 7 two-stage) performed a total of 273 assays using three freeze-dried preparations of differing purity (a plasma, an intermediate and a high purity concentrate). The results of assays with each participant using their normal system established that, if the participants were a representative cross-section, approximately one-third of one-stage laboratories would show a systematic difference from the overall mean of at least 16%, with a similar figure for the two-stage laboratories of 9%. Various features of the assay systems were then modified in a controlled series of experiments. The results showed conclusively that i) differences between reagents accounted for most of the variation between laboratories and, ii) the two-stage assays were, on average, detecting relatively more activity in the more purified preparations than the one-stage assays. The results also suggested that the use of buffer as opposed to haemophilic plasma for the initial dilution of concentrates did not affect the assay results.

scholarly journals A Study on the Performance of a Cascade Heat Pump for Generating Hot Water

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4313 ◽  
Author(s):  
Boahen ◽  
Choi
Keyword(s):  
Heat Exchanger ◽  
Energy Saving ◽  
Heat Pump ◽  
Heat Pumps ◽  
Hot Water ◽  
Research Interest ◽  
Coefficient Of Performance ◽  
Energy Saving Potential ◽  
Heating Capacity

The use of cascade heat pumps for hot water generation has gained much attention in recent times. The big question that has attracted much research interest is how to enhance the performance and energy saving potential of these cascade heat pumps. This study therefore proposed a new cycle to enhance performance of the cascade heat pump by adopting an auxiliary heat exchanger (AHX) in desuperheater, heater and parallel positions at the low stage (LS) side. The new cascade cycle with AHX in desuperheater position was found to have better performance than that with AHX at heater and parallel positions. Compared to the conventional cycle, heating capacity and coefficient of performance (COP) of the new cascade cycle with AHX in desuperheater position increased up to 7.4% and 14.9% respectively.

The Relation between Staphylocoagulase Reacting Factor and Proteins Induced by Vitamin K Absence

1975 ◽  
Author(s):  
B. M. Bas ◽  
A. D. Muller ◽  
H. G. Hemker
Keyword(s):  
Vitamin K ◽  
Vitamin K Antagonists ◽  
The Other ◽  
Two Stage ◽  
One Stage ◽  
Echis Carinatus ◽  
The Difference ◽  
The One ◽  
Factor Assay

Five different ways of estimating prothrombin are applied to the plasma of persons receiving vitamin K antagonists, to know: the one-stage assay, the two-stage assay, the Echis Carinatus Venom assay, the coagulase-reacting factor assay and the immunological assay. The Protein Induced by Vitamin K Absence analogous to prothrombin (PIVKA-II) can be shown to be co-estimated in all but the one-stage assay. There are minor differences, however, between the other four tests. The most practical way to assess both prothrombin and PIVKA-II seems to be the coagulase-reacting factor assay. The difference between the one-stage assay and the others can be explained on basis of the new data on the role of vitamin K in prothrombin biosynthesis. The differences between the other tests are smaller and remain to be explained.

scholarly journals Plasma Transfusions in Hemophilia

Blood ◽  
1952 ◽  
Vol 7 (7) ◽  
pp. 710-720 ◽  
Author(s):  
S. VAN CREVELD ◽  
M. M. P. PAULSSEN
Keyword(s):  
Two Stage ◽  
Coagulation Time ◽  
Prothrombin Activity ◽  
Lasting Effect ◽  
One Stage ◽  
The One ◽  
Rapid Appearance

Abstract Transfusions of heparinized plasma have a greater and more lasting effect on the coagulation time of hemophiliacs than transfusions of citrated plasma. Both in vitro and in vivo, heparinized plasma causes in hemophiliacs a far greater consumption of prothrombin as determined with the two-stage method than citrated plasma. In using the one-stage method no important differences in prothrombin activity are found after transfusions of heparinized and of citrated plasma respectively. This fact was thought to be connected with the more or less rapid appearance of an accelerator. Its a hemophiliac with a circulating anticoagulant, transfusions of heparinized plasma were unable to shorten the coagulation time to any important degree, nor did these transfusions cause an important decrease of serum prothrombin as determined by the two-stage method.

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