Fu-yun Zhao

Publications of Fu-yun Zhao

• CFD Modeling of Built Air Environment in Historic Settlements: Village Microclimate

  Authors: Li Tang, M. Nikolopoulou, Fu-yun Zhao, Nan Zhang

  Computer Distributed Control and Intelligent Environmental Monitoring (CDCIEM), 2011 International Conference on; 03/2011

  Historic settlements have adapted to the local climate and geographical environment accommodating residents over the years. Rich and precious scientific design concepts, including the site selection,Historic settlements have adapted to the local climate and geographical environment accommodating residents over the years. Rich and precious scientific design concepts, including the site selection, the layout, and the building materials, should be investigated extensively. Different historic settlements will be presented and discussed, in terms of different design elements and urban planning forms, and through the use of computational fluid dynamics(CFD). This paper presents the strategic ideas behind the research thinking and methodology of the project. As illustrative case studies, the ambient wind environment within the Shang-Gan-Tang village in China and the Pierce bridge, Melling, Hawks head, Castle Combe villages in the UK, have been investigated quantitatively, to evaluate the interactions between settlement selection, layout, landscape design and ambient environment. The sustainable urban planning experiences were then summarized for the modern sustainable human settlement suitable for people living for another hundreds of years.

• The effects of Bleomycin A5 on infantile maxillofacial haemangioma.

  Authors: Quan-feng Luo, Fu-yun Zhao

  Head & face medicine. 01/2011; 7:11.

  To examine the effects of bleomycin A5 on infantile maxillofacial haemangiomas. Bleomycin A5 was given by multiple intralesinoal injections and the dosage was given according to the age of theTo examine the effects of bleomycin A5 on infantile maxillofacial haemangiomas. Bleomycin A5 was given by multiple intralesinoal injections and the dosage was given according to the age of the patient and size of the lesion. Parts of patients were accompanied by prednisone treatment (2-5 mg/kg, po, QOD. All the haemangiomas involutes completely after treated with bloemycin A5 with better recovery of skin color and less scar forming in small haemangiomas. Infantile haemangioma could be effectively treated with bleomycin A5 without serious side effects.

• [A preliminary study of murine hemangioma model by delivery of recombinant adeno-associated virus mediated human vascular endothelial growth factor-121 gene]

  Authors: Zhen Qi Xu, Yi-Xiang Wang, Juan-Hong Meng, Wei Zhang, Fu Yun Zhao, Yu Liu

  Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology. 04/2009; 44(3):162-4.

  OBJECTIVE: To investigate the feasibility of establishing a murine hemangioma model with injection of recombinant adeo-associated virus mediated human vascular endothelial growth factor-121OBJECTIVE: To investigate the feasibility of establishing a murine hemangioma model with injection of recombinant adeo-associated virus mediated human vascular endothelial growth factor-121 (rAAV-hVEGF(121)) gene. METHODS: rAAV-hVEGF(121) was constructed, identified and then implanted to the left back ear of each mouse (1.0 x 10(11)VG in 50 microl per mouse and 10 nude mice received the injection), the rights served as controls with an injection of the same volume of phosphate buffered solution (PBS). The skin color and swelling of left back ear were observed every other day. Histological examination was carried out after mice were sacrificed 2, 4, 6, 8, 12 weeks after injection. RESULTS: The rAAV-hVEGF(121) was correctly constructed and confirmed by restriction endonuclease analysis, polymerase chain reaction and DNA sequencing analysis. The skin of left back ear became red 2 weeks after injection and gradually exhibited a red lump which was at its utmost 12 weeks after injection. Such phenomena were not observed in right back ear. Histological examinations showed aggregates of endothelial cells by 2 weeks and at 8 weeks the swollen tissue contained many cysts filled with a mass of red cells. CD-34 staining suggested most of the newly-formed cells were endothelial cells. CONCLUSIONS: A hemangioma model was established in mice with injection of recombinant rAAV-hVEGF(121) gene.

• [Dignosis and therapy on hemangiomas and vascular malformation in view of the new classification.]

  Authors: Fu Yun Zhao, Yan Gao, Mei Juan Wu, Quan Feng Luo, Yu Liu, Zhen Qi Xu

  Beijing da xue xue bao. Yi xue ban = Journal of Peking University. Health sciences. 03/2009; 41(1):21-7.

  Vascular birthmarks are the most common disease. The morbidity is about 2.5%, most of the lesions occur in oral and maxillofacial regions which accounts for 40%-60% of the total lesions. In 1982,Vascular birthmarks are the most common disease. The morbidity is about 2.5%, most of the lesions occur in oral and maxillofacial regions which accounts for 40%-60% of the total lesions. In 1982, Mulliken and Glowacki proposed a biologic classification of vascular birthmarks on the basis of their clinical manifestations, histopathological features, and natural history. They defined hemangiomas as vascular tumors with a growth phase, marked by endothelial proliferation and hypercellularity, and an involutional phase. They recognized that many entities referred to as hemangiomas are actually structural alformations of the vasculature, derived from capillaries, veins, lymph vessels, or arteries or from a combination of these sources. The classification was confirmed and issued by International Society for the study of vascular anomality (ISSVA) in 1988. Waner and Suen amended the above category in 1995. This paper presents the new classification of vascular birthmarks and the developments in this field in recent years, including the pathology, clinical features and the therapy. For example, the classification of venular malformation categorized by Waner in 1989; the classification of lymphous malformation by Waner and Suen in 1995; and the treatments according to above classifications.

• [Therapeutic effects of Avastin on the murine hemangioendothelioma.]

  Authors: Zhen Qi Xu, Yu Liu, Yi-Xiang Wang, Wei Zhang, Fu Yun Zhao

  Beijing da xue xue bao. Yi xue ban = Journal of Peking University. Health sciences. 02/2009; 41(1):105-8.

  OBJECTIVE: Investigated the efficacy of Avastin on murine hemangioendothelioma in vitro and in vivo using a mouse hemangioendothelioma-derived cell line----EOMA. METHODS: The in vitro effect ofOBJECTIVE: Investigated the efficacy of Avastin on murine hemangioendothelioma in vitro and in vivo using a mouse hemangioendothelioma-derived cell line----EOMA. METHODS: The in vitro effect of Avastin on cell proliferation of EOMA cell line was measured by CCK-8 assay at 0, 50, 100, 200 mg/L concentration of Avastin. When tumors produced by subcutaneous injection of EOMA cells reached a volume of 100 mm(3), animals were treated by intra-tumor injection with Avastin (1 mg/kg body weight) or with vehicle alone (PBS) twice a week. Mice were weighted and tumors were measured three times weekly. At the end of the experiment, the mice were sacrificed and their tumors were excised and processed for histology. Immunohistochemical study of apoptosis was conducted using a TUNEL kit, tumor cell proliferation was assessed with anti-proliferating cell nucler antiger (PCNA) antibody. Cardiac puncture was performed under deep anesthesia for collection of serum, serum vascular endothelial growth factor (VEGF) level was tested by VEGF-ELISA assay. RESULTS: Avastin exhibited cell inhibited rate of 24.21%, 26.26% and 34.58% at 50, 100 and 200 mg/L, respectively. When experiment was terminated, the tumor volume in the PBS-treated mice was (1 860.10+/-146.96) mm(3), being significantly larger than that in the mice that were treated by Avastin [(681.45+/-63.01) mm(3), P<0.01]. Avastin-treated tumors showed decreased tumor cell proliferation and increased cell apoptosis. The VEGF level in mice treated with Avastin [(594.65+/-118.79) ng/L] was significantly lower than that in PBS-treated mice [(802.24+/-238.41) ng/L, P<0.05]. CONCLUSION: The results suggest that topically applied Avastin provides an effective and safe approach to treat hemangioendotheliomas and might be used as a novel treatment of angiomatous diseases in the future.

• Reconstruction of a huge oral maxillofacial defect caused by necrotic fasciitis secondary to leukaemia.

  Authors: Hui-Min Chen, Zhi-Gang Cai, Fu-yun Zhao, Jiang Wu, Ruo-Ping Jiang

  Journal of plastic, reconstructive & aesthetic surgery : JPRAS. 09/2008;

  An 8-year-old boy who was diagnosed with 'acute non-lymphoblastic leukaemia (M2)', contracted secondary oral maxillofacial necrotic fasciitis. The wound was cleaned with 3% hypertonic saline, andAn 8-year-old boy who was diagnosed with 'acute non-lymphoblastic leukaemia (M2)', contracted secondary oral maxillofacial necrotic fasciitis. The wound was cleaned with 3% hypertonic saline, and then covered with iodoform gauze every day for about 3 weeks before and after necrotic tissue debridement. The local infection was controlled, and plenty of new healthy granular tissue had grown. The patient was left with a huge defect including the mouth floor, submental area, submandibular area and right cheek when the necrotic tissue was removed. Reconstruction of the defect was very difficult because of the patient's pre-existing leukaemia condition and severe inflammatory local condition. We successfully reconstructed the defect by using the new healthy granular tissue and a trapezius myocutaneous flap. During 9 years of follow up, in order to improve quality of life, the patient underwent scar modification surgery and orthodontic treatment, and facial appearance and oral functions were deemed satisfactory.

• Evaluation of near infrared spectroscopy in monitoring postoperative regional tissue oxygen saturation for fibular flaps.

  Authors: Zhi-Gang Cai, Jie Zhang, Jian-Guo Zhang, Fu-yun Zhao, Guang-Yan Yu, Yue Li, Hai-shu Ding

  Journal of plastic, reconstructive & aesthetic surgery : JPRAS. 02/2008; 61(3):289-96.

  The ability of near infrared spectroscopy (NIRS) to predict vascular compromise in vascular free flaps postoperatively has been assessed, and the extent of regional tissue oxygen saturation (rSO(2))The ability of near infrared spectroscopy (NIRS) to predict vascular compromise in vascular free flaps postoperatively has been assessed, and the extent of regional tissue oxygen saturation (rSO(2)) after fibular flap transplantation was investigated quantitatively. To validate the sensibility and precision of the technique, the following methods were used. (1) Forearm vessel obstructive tests were conducted in four healthy volunteers. (2) Measurement and analysis of bilateral rSO(2) at the mandibular body and ramus were performed in 40 healthy volunteers by NIRS in the morning and afternoon. (3) Measurement and analysis of rSO(2) in transplanted fibular flaps for 41 cases with mandibular reconstruction were performed by NIRS at postoperative days 1-6. The results were: NIRS had high sensibility and precision in monitoring rSO(2) of living tissues. No significant difference in the values of rSO(2) was found across different times or areas in the normal mandible. However, rSO(2) in the transplanted fibular flaps was reduced compared to the value on the control side. rSO(2) decreased gradually 4-12 hours postoperatively. After that period, rSO(2) increased gradually and approached the value of the control side at 20 h after the operation. It can be concluded that NIRS is a reliable noninvasive method for monitoring blood circulation in transplanted tissues, particularly for buried flaps.

• A preliminary study of angiographic classification and its correlation to treatment of central arteriovenous malformation in the jaw.

  Authors: Deng-gao Liu, Xu-chen Ma, Fu-yun Zhao, Jian-Guo Zhang

  Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics. 11/2005; 100(4):473-80.

  OBJECTIVE: To elaborate on the classification of central arteriovenous malformations (AVMs) in the jaw based on angioarchitecture and to evaluate the correlation of this classification with treatmentOBJECTIVE: To elaborate on the classification of central arteriovenous malformations (AVMs) in the jaw based on angioarchitecture and to evaluate the correlation of this classification with treatment options. STUDY DESIGN: X-ray films and digital subtraction angiograms (DSA) of 25 cases with AVMs in the jaw were retrospectively reviewed to evaluate the appearance of bone resorption, feeding arteries, nidus of the malformations, and draining veins. Based on the findings a classification of angioarchitecture was recommended. Furthermore, the treatment results of these cases were reviewed to assess the correlation of this classification system with treatment options. RESULTS: The angiographic pictures of 25 cases with central AVMs could be divided into 5 types: Type I (n = 5) had diffused microarteriovenous fistulas (AVFs); type II (n = 8) had 1 large venous pouch with all the feeding arteries draining into it; type III (n = 7) had a large venous pouch as well as diffused microAVFs (I+II); type IV (n = 2) had multiple venous pouches; and type V (n = 3) had multiple venous pouches and diffused microAVFs (I + IV). The angioarchitecture corresponded well to the x-ray appearance in all cases except 1 (96%). With respect to the treatment outcomes, type II, III, and IV AVMs gained clinical cure in 100% of the cases, whereas type I and type V AVMs obtained clinical cure only in 60% and 33.3% of the cases, respectively. CONCLUSIONS: Central AVMs in the jaw contained variant patterns of angioarchitecture and could be divided into 5 types. This angiographic classification was helpful for decision making about appropriate therapy.

• [Diagnosis and management of 49 cases of hemangiomas in infants and children]

  Authors: Xiang-hui Zeng, Fu-yun Zhao, Jian-Guo Zhang, Zhen-kang Zhang, Guang-Yan Yu, Dong-Mei He

  Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology. 06/2005; 40(3):187-90.

  OBJECTIVE: To observe the management results of hemangioma in infants and children. METHODS: Forty-nine cases of hemangioma in infants and children managed from 1986 to 2004 were reviewed. During theOBJECTIVE: To observe the management results of hemangioma in infants and children. METHODS: Forty-nine cases of hemangioma in infants and children managed from 1986 to 2004 were reviewed. During the management period, the incidence and first visit age and sex were recorded. The location and volume of the lesions were photographed and followed up at an interval of 3 to 12 months until the complete involution of the tumor. The treatment modalities used included local injection of prednisone in 16 cases, surgery in 6 cases, and the remaining 33 cases were observed without treatment. RESULTS: Thirty-three cases receiving no treatment involuted naturally. The complete involution age was found from 9 months to 10 years with average age of 5.4 years. The cosmetic results after involution were good. CONCLUSIONS: Most nemaugiomas do not need treatment and can involute naturally. However, in cases with severe complications such as expausion, destruction and obstructive or congestive heart failure, treatment is indicated.

• [A preliminary study of angiographic classification and treatment of central arteriovenous malformations in jaws]

  Authors: Deng-gao Liu, Xu-chen Ma, Fu-yun Zhao, Jian-Guo Zhang

  Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology. 06/2005; 40(3):195-9.

  OBJECTIVE: To elaborate on the angiographic classification of central arteriovenous malformations (AVMs) in jaws, and to evaluate the correlation between this classification and treatment options.OBJECTIVE: To elaborate on the angiographic classification of central arteriovenous malformations (AVMs) in jaws, and to evaluate the correlation between this classification and treatment options. METHODS: X-ray films and angiograms of 25 cases with AVMs in the jaw were retrospectively reviewed to evaluate the appearance of radiolucency, feeding arteries, nidus of the malformations and draining veins. Based on the findings a classification of angioarchitecture was recommended. Furthermore, the treatment results of these cases were reviewed to assess the correlation between this classification and treatment options. RESULTS: The angiographic pictures of 25 cases with central AVMs could be divided into five types: type I (n = 5) was with merely diffused micro-arteriovenous fistulas (AVFs); type II (n = 8) demonstrated a large venous pouch, all the feeding arteries drained into it; type III (n = 7) had a large venous pouch together with diffused micro-AVFs (I + II); type IV (n = 2) had multiple venous pouches; type V (n = 3) had multiple venous pouches and diffused micro-AVFs (I + IV). The angioarchitecture corresponded well to the radiographic appearance in all except one case. With respect to the treatment, type II, III, IV AVMs gained clinical cure in 100% of cases, whereas type I and type V AVMs obtained clinical cure only in 3 of 5 and 1 of 3 cases respectively. CONCLUSIONS: Central AVMs in jaws exhibited variant patterns of angioarchitecture, which could be divided into five types. Elaboration of this classification was helpful for decision-making on choosing appropriate therapy.

• Numerical analysis of two contaminants removal from a three-dimensional cavity

  Authors: Di Liu, Fu-Yun Zhao, Guang-Fa Tang

  International Journal of Heat and Mass Transfer.

  This paper reports the results of a numerical study on removal of two contaminants from a three-dimensional enclosure with one inlet, one exhausting port and one returning port. In the formation ofThis paper reports the results of a numerical study on removal of two contaminants from a three-dimensional enclosure with one inlet, one exhausting port and one returning port. In the formation of the problem, use is made of Reynolds stress model (RSM). The governing equations are solved by means of the SIMPLE algorithm. Lots of cases have been studied for the sensitivity analysis, including more practical cases from the total fresh air supplying to the total recirculation situations. The influence of inlet velocity, fresh air ratio, recirculating air filtered removal efficiency and contaminant property is investigated. The indoor contaminant is studied parametrically as a function of governing dimensionless numbers (Reynolds number and Schmidt number). The results show the above parameters have complex influence to indoor contaminant removal.

• Photodynamic therapy in the treatment of malignant tumours: An analysis of 540 cases

  Authors: Jun-Heng Li, Zhong-He Guo, Mao-Lin Jin, Fu-Yun Zhao, Wei-Ming Cai, Men-Lin Gao, Ming-Yan Shu, Jin Zou

  Journal of Photochemistry and Photobiology B: Biology.

  Malignant tumours (540 cases), including tumours of the lung, oesophagus, cardia, stomach, rectum, bladder, other urinary genital organs, face and mouth, eyes, ear, nose and throat (ENT), head andMalignant tumours (540 cases), including tumours of the lung, oesophagus, cardia, stomach, rectum, bladder, other urinary genital organs, face and mouth, eyes, ear, nose and throat (ENT), head and neck, breast and skin, were treated using photodynamic therapy (PDT) between 1982 and 1985 in Beijing. All of the cases were identified pathologically and the patients received haematoporphyrin derivative (HPD) (5 mg kg−1) intravenously 48–72 h prior to PDT. An argon-pumped dye laser emitting at 630 nm was used for the treatment. The results were as follows: complete response (CR) was obtained in 227 cases (42.1%), partial response (PR) was obtained in 114 cases (21.1%), mild response (MR) was obtained in 120 cases (22.2%) and 79 cases (14.6%) showed no response (NR). The effectiveness of PDT in the different organs was compared. HPD fluorescence was examined in 409 cases of malignant tumours: 344 lesions (84.1%) revealed red fluorescence (positive reaction), 32 gave an equivocal response and 33 gave a negative reaction. Positive fluorescence was seen in all types of malignant tumour in our study. Indications and limitations of PDT for the different organs are discussed and compared.

• Numerical determination of boundary heat fluxes in an enclosure dynamically with natural convection through Fletcher–Reeves gradient method

  Authors: Fu-Yun Zhao, Di Liu, Guang-Fa Tang

  Computers & Fluids.

  An iterative Fletcher–Reeves conjugate gradient method (CGM) is adopted to estimate the boundary heat fluxes in a fluid-saturated enclosure, where the fluid flow is dynamically coupled with the heatAn iterative Fletcher–Reeves conjugate gradient method (CGM) is adopted to estimate the boundary heat fluxes in a fluid-saturated enclosure, where the fluid flow is dynamically coupled with the heat convection. The sets of direct, sensitivity and adjoint equations required for the solution of the inverse problem are formulated in terms of an arbitrary domain in two dimensions. The methodology of conjugate gradient method solves the inverse natural convection problem satisfactorily without any a priori information about the unknown heat fluxes. The pressure-correction method is utilized to solve the continuum direct, sensitivity and adjoint problems by enforcing global mass and energy conservations. Effects of boundary heat flux profile and thermal Rayleigh number on the convective heat transport are investigated. The effects of position and number of temperature sensors on the inverse problem solution are also addressed in this paper. Inverse solutions of noise data are regularized with the Discrepancy Principle of Alifanov; otherwise, the high frequency components of the random noise were reproduced.

• Thermosolutal convection in saturated porous enclosure with concentrated energy and solute sources

  Authors: Di Liu, Fu-Yun Zhao, Guang-Fa Tang

  Energy Conversion and Management.

  Double diffusive natural convection within a vertical porous enclosure with localized heating and salting from one side is numerically studied by the finite element based finite volume method. In theDouble diffusive natural convection within a vertical porous enclosure with localized heating and salting from one side is numerically studied by the finite element based finite volume method. In the formulation of the problem, use is made of the Darcy model, which allows the slip boundary condition on a solid wall to be satisfied. Comparisons with benchmark solutions for natural convection in fluid saturated porous enclosures are first presented to validate the code. Following that, an extensive series of numerical simulations is conducted in the range of −55 ⩽ N ⩽ + 55 and 0.125 ⩽ L ⩽ 0.875, where N and L are the buoyancy ratio and the element location, respectively. Streamlines, heatlines, masslines, isotherms and iso-concentrations in the system are produced to illustrate the flow structure transition from solutal dominated opposing to thermal dominated and solutal dominated aiding flows, respectively. The computed average Nusselt and Sherwood numbers provide guidance for locating the heating and salting element.

• Application issues of the streamline, heatline and massline for conjugate heat and mass transfer

  Authors: Fu-Yun Zhao, Di Liu, Guang-Fa Tang

  International Journal of Heat and Mass Transfer.

  Functions and lines have been extensively used to visualize two-dimensional fluid, heat and mass transportation structures. However, some ambiguities related to streamlines, heatlines and masslinesFunctions and lines have been extensively used to visualize two-dimensional fluid, heat and mass transportation structures. However, some ambiguities related to streamlines, heatlines and masslines still exist, especially for conjugate heat and mass transfer in anisotropic media. Present work aims to clarify these issues from numerical viewpoints, mainly including diffusion coefficient of transportation function at the interface of different media, different numerical approaches for solving visualization functions, non-dimensional forms of heatfunction and massfunction matching the spatial Nusselt and Sherwood numbers. The numerical procedures and code routines for the primitive conserved variables and the functions are illustrated through visualizing fluid, heat and solute transportations of double diffusive natural convection in square enclosures with massive walls or center-inserted body.

• Non-unique convection in a three-dimensional slot-vented cavity with opposed jets

  Authors: Di Liu, Fu-Yun Zhao, Guang-Fa Tang

  International Journal of Heat and Mass Transfer.

  This study aims to investigate multiple flow structures in a three-dimensional chamber with opposed jets. Numerical computations focus on the effect of inlet velocity on the air flow pattern,This study aims to investigate multiple flow structures in a three-dimensional chamber with opposed jets. Numerical computations focus on the effect of inlet velocity on the air flow pattern, especially on multiple steady flow characteristics for Reynolds maintaining 105. Three distinct branches of steady-state flows are found for this configuration. A complete study of stability of each branch is performed for varying velocity of the left inlet continuously between 0 and 3. The results are presented by stability diagrams showing the critical parameters corresponding to transition from one steady-state branch to the other state within multiple flow range. In parallel with numerical development, an experimental system was set up where adjustable flow rate was prescribed to produce variation of supplying jets. The corresponding vector flow fields, on a scale model, were measured by a laser-based particle image velocimetry (PIV) system. The multiple flow structures were validated both by numerical simulation and experimental investigation.

• Active low-grade energy recovery potential for building energy conservation

  Authors: Di Liu, Fu-Yun Zhao, Guang-Fa Tang

  Renewable and Sustainable Energy Reviews.

  With environmental protection and energy source posing as the biggest issue of the global problems, human beings have no choice but to reduce energy consumption. One way to accomplish this is toWith environmental protection and energy source posing as the biggest issue of the global problems, human beings have no choice but to reduce energy consumption. One way to accomplish this is to increase the efficiency of energy consumption and sufficiently exploit the low-grade energy in our lives. Low-grade energy recovery devices are of significance to meet the needs for energy conservation and green environment requirements such as fresh air pre cooling/heating, water heating, drying clothes and humidifying. These devices are also free of motion parts, non-corrosive and environmentally friendly. Various low-grade energy recoveries powered cooling, heating, drying and dehumidifying systems have been tested extensively; however, these systems are not yet ready to compete with the well-known vapor-compression system. The objective of this paper is to provide fundamental knowledge on the low-grade energy usage systems and present a detailed review on the past efforts in the field of low-grade energy recovery and usage subsystems. Lots of attempts have been made by the researchers to improve the performance of the low-grade energy recovery or usage subsystems. It is seen that, for successful operation of such systems, combination of diverse technologies is essential for more effective and multi-purpose applications.

• Resonant response of fluid flow subjected to discrete heating elements

  Authors: Fu-Yun Zhao, Di Liu, Guang-Fa Tang

  Energy Conversion and Management.

  Two-dimensional calculation and theoretical analysis have been performed for laminar natural convection induced by two discrete heating elements flush mounted to one vertical wall of a squareTwo-dimensional calculation and theoretical analysis have been performed for laminar natural convection induced by two discrete heating elements flush mounted to one vertical wall of a square enclosure. Two cases are presented in this work. One is the upper elevation Heater-1 fluctuates its temperature as a sinusoidal function while the lower elevation Heater-2 maintains its temperature constant. The other case depicts the opposite situation of interchanging the boundary conditions of Heater-1 and Heater-2 in Case 1. A large range (0.01–10.0) of non-dimensional frequency is conducted numerically, and the results show the existence of resonance frequencies in both cases. Scale analysis over predicts the resonance frequency due to ignoring heat dissipation between the heaters. Mechanical details of the fluid flow and average heat transfer characteristics across Heater-1, Heater-2 and the centerline of the enclosure are scrutinized. The results indicate that in Case 1, the heat transfer of Heater-2 is little affected by the periodic change of temperature of Heater-1. However, the oscillatory behavior is largely intensified in Case 2 owing to the thermal wake generated on Heater-2 invigorating the global flow throughout the enclosure. The heatline concept, flow and temperature fields of the oscillating components are adopted to visualize the heat transport and fluid circulation.

• Modeling and experimental investigation of looped separate heat pipe as waste heat recovery facility

  Authors: Di Liu, Guang-Fa Tang, Fu-Yun Zhao, Han-Qing Wang

  Applied Thermal Engineering.

  A looped separate heat pipe as waste heat recovery facility for the air-conditioning exhaust system has been developed in this work. A one-dimensional steady-state model is presented for determiningA looped separate heat pipe as waste heat recovery facility for the air-conditioning exhaust system has been developed in this work. A one-dimensional steady-state model is presented for determining the upper and lower operating boundaries of the initial filling ratio of the working fluid, as a function of the separate heat pipe geometry, vapor temperature of working fluid and power throughput, combined with two-phase heat exchange characteristics and distribution of the liquid film velocity along with the liquid film thickness direction. A parametric analysis is performed to investigate the effects of the length of the evaporator, vapor temperature, and power throughput on the critical values of the upper and lower boundaries. Simulation results show that the length of the evaporator makes almost no influence on the upper boundary, but great effect on the lower boundary. An increase of the vapor temperature leads to the easier arriving of the lower boundary. Moreover, operation ranges of the separate heat pipe vary with the working fluids. Water and methanol were used separately. An experiment was implemented to validate the simulated results. The numerical predictions compare favorably with experimental results.

• Natural convection in a porous enclosure with a partial heating and salting element

  Authors: Fu-Yun Zhao, Di Liu, Guang-Fa Tang

  International Journal of Thermal Sciences.

  This paper reports a numerical study of double-diffusive convective flow of a binary mixture in a porous enclosure subject to localized heating and salting from one side. The physical model for theThis paper reports a numerical study of double-diffusive convective flow of a binary mixture in a porous enclosure subject to localized heating and salting from one side. The physical model for the momentum conservation equation makes use of the Darcy–Brinkman equation, which allows the no-slip boundary condition on a solid wall to be satisfied. The set of coupled equations is solved using the SIMPLE algorithm. An extensive series of numerical simulations is conducted in the range of −15⩽N⩽+14, 10−3⩽Le⩽102, 10−8⩽Da⩽102 and 0.125⩽L⩽0.875, where N, Le, Da and L are the buoyancy ratio, Lewis number, Darcy number and the segment location. Results for a pure viscous fluid and a Darcy (densely packed) porous medium emerge from the present model as limiting cases. Streamlines, heatlines, masslines, isotherms and iso-concentrations are produced for several segment locations to illustrate the flow structure transition from solutal-dominated opposing to thermal dominated and solutal-dominated aiding flows, respectively. The segment location combining with Lewis number is found to influence the buoyancy ratio at which flow transition and flow reversal occurs. The computed overall Nusselt and Sherwood numbers provide guidance for locating the heating and salting segment.