Modelling of Heat Transfer in Ground Heat Exchangers

The results of the numerical simulation of heat conduction in ground with a horizontal, tubular (parallel pipes) heat exchanger installed are presented in this paper. On the basis of analysis of courses of temperature isolines in the ground, a simplified mathematical heat transfer model in a horizontal ground exchanger was developed. The ground thermal diffusivity was assumed to be a variable of location. On the basis of the model, the temperature profiles in the ground with a heat exchanger installed were determined

Heat Transfer Model to Predict Temperature Distribution in the Ground

Knowledge of the temperature of the ground in time and space as well as its thermal properties gives basic information about physical phenomena concerning the transfer and accumulation of heat in the ground. It can be also used for evaluation of the heating possibilities of heat pumps; to proper design the size of the ground exchangers and the depth, at which they should be installed. For this purpose, a mathematical model based on the heat balance equation on the ground surface was developed. The basis of the model is the Carslaw-Jaeger equation regarding the temperature profile in the ground. The model was verified using experimental results for two different locations (different climatic conditions, moderate and arid climate)—the standard deviation is equal 0.62 K and 0.92 K, respectively. In this work, the impact of several parameters on the ground temperature profiles and thermal fluxes was determined. It was found that among the examined parameters the amplitude of the daily average solar radiation flux strongly effects on the total amount of heat transferred between the ground and the environment during the year, wherein the other parameters have a negligible effect

Physiotherapy in a scoliotic posture with asymmetry of movements in temporomandibular joints - case study

Wstęp: Wiek rozwojowy jest czasem, w którym najczęściej dochodzi do różnych odchyleń w postawie ciała. Postawa skoliotyczna jest pierwszym etapem każdej rozwijającej się skoliozy, zaliczanej do najczęściej występujących ortopedycznych chorób u dzieci oraz młodzieży. W kontroli postawy swój udział ma układ stomatognatyczny, do którego zalicza się stawy skroniowo-żuchwowe.Cel pracy: Przedstawienie pacjentki z postawą skoliotyczną oraz asymetrią ruchów w stawach skroniowo-żuchwowych. Ocena postępu jej rehabilitacji za pomocą komputerowego badania postawy ciała. Materiał i metody: Materiał stanowi dokumentacja medyczna oraz wyniki komputerowego badania postawy ciała trzynastoletniej dziewczynki z cechami postawy skoliotycznej do 10 stopni, asymetrią ruchów w stawach skroniowo-żuchwowych oraz wadą zgryzu - tyłozgryz. W badaniu pacjentki przeprowadzono wywiad, kliniczną ocenę postawy oraz komputerowe badanie postawy ciała. Użyto aparatury, która swoje działanie opiera na metodzie fotogrametrycznej oraz efekcie mory projekcyjnej. W trakcie badania wykonana została komputerowa fotografia (przy użyciu kamery wideo). Za pomocą specjalnego systemu optycznego wyznaczony został trójwymiarowy obraz pleców, a komputer dokonał analizy parametrów w płaszczyźnie zarówno strzałkowej jak i czołowej.Wyniki: Zaobserwowano wyrównanie asymetrii w ruchach stawów skroniowo-żuchwowych oraz odnotowano poprawę w niektórych parametrach w komputerowym badaniu postawy ciała. Podsumowanie i wnioski: Prowadzona w odpowiedni sposób rehabilitacja, a także stosowanie się do zaleceń przez pacjentkę i jej rodziców wpłynęło na poprawę parametrów w badaniu komputerowym oraz badaniu klinicznym.Introduction: The developmental period is the time, in which the most common deviations occur in the posture of the body. The scoliotic posture is the first stage of every developing scoliosis, one of the most common orthopedic diseases in children and adolescents. The stomatognathic system, which includes temporomandibular joints, contributes to control the posture.Aim of the study: Presentation of case - the girl with a scoliotic posture and asymmetry of movements in the temporomandibular joints. Evaluation of the progress of the rehabilitation by means of a computer examination of body posture.Material and methods: The materials are medical documentation and the results of a computer body posture examination of thirteen-year-old girl with scoliotic posture, asymmetry of movements in the temporomandibular joints and malocclusion - posterior bite. The patient's examination included an interview, a clinical assessment of the posture of her body and a computerized examination of body posture. Equipment was used, which operates based on the photogrammetric method and the effect of the projection moiré. During the examination, a computer photograph was made (using a video camera). Using a special optical system, a three-dimensional image of the back was determined, and the computer analyzed parameters in both sagittal and frontal planes.Results: Equalization of asymmetry in temporomandibular joint movements was observed as well as an improvement in some parameters in the computerized postural examination.Summary and conclusions: Rehabilitation carried out in an appropriate methodology, as well as adherence to recommendations by the patient and her parents resulted in improved parameters in the computer examination and clinical examination

Study of temperature distribution in the ground

Knowledge of the temperature distribution in subsurface layers of the ground is important in thedesign, modelling and exploitation of ground heat exchangers. In this work a mathematical model ofheat transfer in the ground is presented. The model is based on the solution of the equation of transientheat transfer in a semi-infinite medium. In the boundary condition on the surface of the groundradiation fluxes (short- and long-wave), convective heat flux and evaporative heat flux are taken intoaccount. Based on the developed model, calculations were carried out to determine the impact ofclimatic conditions and the physical properties of the ground on the parameters of the Carslaw-Jeagerequation. Example results of calculated yearly courses of the daily average temperature of the surfaceof the ground and the amount of particular heat fluxes on the ground surface are presented. Thecompatibility of ground temperature measurements at different depths with the results obtained fromthe Carslaw–Jaeger equation is evaluated. It was found thatthe temperature distribution in the groundand its variability in time can be calculated with good accuracy

Undisturbed Ground Temperature—Different Methods of Determination

Methods for the calculation of the undisturbed ground temperature (UGT) are presented. Heat fluxes occurring on the surface of the ground and their influence on the UGT are described. Correlation equations for the calculation of the undisturbed ground temperature based on the meteorological data averaged in the yearly cycle are proposed. These equations are of a semi-empirical character and they are based on the heat flux balance. The determined coefficients of these equations, particularly the convection heat transfer coefficient, are consistent with the values specified by other methods

Thermal performance of a PCM integrated underfloor heating system. Experimental and numerical analysis

The application of Phase Change Materials (PCMs) in radiant floor heating considerably enhance their energy saving potential and the improvement of indoor thermal comfort as well. The study aims at investigating the energy performance of a PCM integrated hydronic underfloor heating system in dry and wet sand conditions. Experimental and numerical analysis of floor surface temperature and heat flux demonstrated that higher thermal conductivity of sand increases more quickly the thermal performance of the system