Heat exchanger selection

"Excel spreadsheet Build-Heat-Exchanger.xls predicts the microbial spoilage rate, the % nutrient retention, the F value, the Biological index B*,  and the Chemical index C*, received by a liquid food after flowing through a heat exchanger.
The program can also be used to calculate the exact residence time in the heat exchanger holding tube, required  to give a liquid food a specified F value. Or to find the best residence times and temperatures to get a particular  lower microbial or enzymatic spoilage rate, combined with an optimal % nutrient retention.
A correction factor for residence time distribution is included in the program.
Build-Heat-Exchanger.xls also shows the effects of a reduced food flow in the heat exchanger on the F value, on the microbial spoilage rate, and on the % nutrient retention of a heated liquid food.
A worked example is included in the spreadsheet, showing how to use Build-Heat-Exchanger.xls."

"Excel spreadsheet Build-Heat-Exchanger.xls, down-loadable from this website, was developed to predict the microbial spoilage rate, the % nutrient retention, the F value, the Biological index B*,  and the Chemical index C*, received by a liquid food after flowing through a heat exchanger.
The program can also be used to calculate the exact residence time in the heat exchanger holding tube, required  to give a liquid food a specified F value. Or to find the best residence times and temperatures to get a particular  lower microbial or enzymatic spoilage rate, combined with an optimal % nutrient retention.
A correction factor for residence time distribution is included in the computer program.
Build-Heat-Exchanger.xls also shows the effects of a reduced food flow in the heat exchanger on the F value, on the microbial spoilage rate, and on the % nutrient retention of a heated liquid food.
The spreadsheet has been validated by comparing the calculation results of B*,  B* (adjusted), C*, and % α-lactalbumin retention, to calculations of the same parameters by a UHT indirect heat exchanger model, developed by Tran et al. (2008).
Several worked examples show how to use Build-Heat-Exchanger.xls."

In addition to their low cost and weight, polymer heat exchangers offer good anticorrosion and antifouling properties. In this work, a cost effective air-water polymer heat exchanger made of thin polymer sheets using layer-by-layer line welding with a laser through an additive manufacturing process was fabricated and experimentally tested. The flow channels were made of 150 μm-thick high density polyethylene sheets, which were 15.5 cm wide and 29 cm long. The experimental results show that the overall heat transfer coefficient of 35–120 W/m2 K is achievable for an air-water fluid combination for air-side flow rate of 3–24 L/s and water-side flow rate of 12.5 mL/s. In addition, by fabricating a very thin wall heat exchanger (150 μm), the wall thermal resistance, which usually becomes the limiting factor on polymer heat exchangers, was calculated to account for only 3% of the total thermal resistance. A comparison of the air-side heat transfer coefficient of the present polymer heat exchanger with some of the commercially available plain plate fin heat exchanger surfaces suggests that its performance in general is superior to that of common plain plate fin surfaces.

محققان دانشگاهی و مهندسین شرکت‌های بزرگ صنعتی در سراسر دنیا به تحقیق و مطالعه در خصوص مبدل‌های حرارتی مشغول می‌باشند که‌حاصل آن در قالب کتب و مقالات متنوعی منتشر شده است. با این حال جدا بودن دو دیدگاه صنعتی و دانشگاهی، از نقاط ضعف عمده این تحقیقات است. نویسندگان این کتاب تلاش کرده‌اند با طرح مباحثی مانند معرفی و بررسی انواع مبدلهای حرارتی، چگونگی انتخاب مبدل، طراحی حرارتی، طراحی مکانیکی، انتخاب مواد، خوردگی در مبدل‌ها، نحوه تمیزکاری، بررسی انواع استانداردهای صنعتی و همچنین آموزش نرم افزارهای مرتبط، مرجعی مناسب جهت مخاطبین هر دو گروه دانشگاهی و صنعتی تهیه کنند.
این کتاب در سه قسمت تقریباً مستقل تهیه شده است. قسمت اول آن به معرفی مبدل¬های رایج پرداخته است. در این بخش سعی شده است که با استفاده از تصاویر مختلف، درک بهتری از مطالب انجام گیرد و همچنین کلیه موارد عمومی مربوط به هر مبدل از جمله جنس مواد، روش ساخت، روش-های تمیزکاری، نقاط قوت و ضعف مبدل به تفکیک بیان شود. مخاطبین این بخش جدا از دانشجویان، صنعتگران و مهندسانی هستند که تنها نیاز به کلیاتی در خصوص هر مبدل دارند. قسمت دوم کتاب به طراحی حرارتی اختصاص یافته است و بخش سوم این کتاب نیز به طراحی مکانیکی مبدل پوسته و تیوب بر اساس کد ASME اختصاص دارد. در نهایت در انتهای کتاب، برخی مطالب کمکی نظیر خوردگی، رسوب¬گذاری و نیز بعضی از جداول لازم جهت طراحی و انتخاب مواد به صورت پیوست آورده شده است.

Heat exchangers are the equipments used to transfer the heat from one fluid to another which are at different temperatures. Different types of heat exchangers are extensively used in various industries to transfer the heat between cold and hot fluids. The key role of the heat exchanger is to transfer heat at maximum rate. Concentric tube heat exchanger has potential application such as heat recovery from engine cooling circuit, oil cooling, de superheating in refrigeration and air conditioning, dairy, and chemical industry, pharmaceutical industry, refinery, etc. In this paper concentric tube heat exchanger is designed and fabricated with inner pipe made of copper and outer pipe made of galvanized iron. The CuO nanoparticles of about30 nm diameter are used in the present study. Nanoparticles were dispersed in the base fluid to enhance the rate of heat transfer and overall heat transfer coefficient. The results shows that heat transfer rate and overall heat transfer coefficient of nano fluid is slightly higher than that of the base liquid at same mass flow rate .The heat transfer rate and overall heat transfer coefficient of nano fluid increases with the increase of the volume concentration of the CuO nano fluid .There is a wide scope on performance of heat exchanger and applications of nano fluid in the coming years.

Heat transfer instruction lessons has been a mainstay in the curriculum of undergraduate and postgraduate programs in mechanical and chemical engineering disciplines in higher institutions across the world. This paper presents the design and fabrication of a shell and tube heat exchanger (STHE) for laboratory experiments. A detailed thermal design using the Kern's approach was adopted for the thermal design of the heat exchanger. Thereafter, a mechanical design was carried out employing the TEMA standards and the ASME BPVC. It was then modeled before its fabrication. A water retention mechanism was designed using PVC pipes and 90˚ bend connectors to form a U-shaped apparatus to ensure efficient exchange of heat between both streams of fluid.

A B S T R A C T In recent years, the study of rheological behavior and heat transfer of nanofluids in the industrial equipment has become widespread among the researchers and their results have led to great advancements in this field. In present study, the laminar flow and heat transfer of water/functional multi-walled carbon nanotube nanofluid have been numerically investigated in weight percentages of 0.00, 0.12 and 0.25 and Reynolds numbers of 1–150 by using finite volume method (FVM). The analyzed geometry is a two-dimensional backward-facing contracting channel and the effects of various weight percentages and Reynolds numbers have been studied in the supposed geometry. The results have been interpreted as the figures of Nusselt number, friction coefficient, pressure drop, velocity contours and static temperature. The results of this research indicate that, the enhancement of Reynolds number or weight percentage of nanoparticles causes the reduction of surface temperature and the enhancement of heat transfer coefficient. By increasing Reynolds number, the axial velocity enhances, causing the enhancement of momentum. By increasing fluid momentum at the beginning of channel, especially in areas close to the upper wall, the axial velocity reduces and the possibility of vortex generation increases. The mentioned behavior causes a great enhancement in velocity gradients and pressure drop at the inlet of channel. Also, in these areas, Nusselt number and local friction coefficient figures have a relative decline, which is due to the sudden reduction of velocity. In general, by increasing the mass fraction of solid nanoparticles, the average Nusselt number increases and in Reynolds number of 150, the enhancement of pumping power and pressure drop does not cause any significant changes. This behavior is an important advantage of choosing nanofluid which causes the enhancement of thermal efficiency.

Channels not receiving the same amount of flow (flow maldistribution) is an important effectiveness loss for high effectiveness heat exchangers. This paper develops a finite difference model of a counter flow heat exchanger. For modeled scenarios very good agreement with previous studies and analytical calculations was achieved. For independent pairs of hot and cold channels, as flow rate is reduced, the effectiveness asymptotically approaches the irregularity parameter (a measure of channel flow maldistribution). With thermal coupling between pairs of channels (measured by an equivalent Peclet number), effectiveness continues to increase with decreasing flow rate. These results hold for uncorrelated flow maldistribution on both sides or no flow maldistribution on one side. However, when flow maldistribution is positively correlated, effectiveness is higher; and, when it is negatively correlated, effectiveness is lower. A number of resulting graphs illustrate the effectiveness for each channel with different flow rate and correlation. While one exemplary application is a polymer expanded microchannel heat exchanger, the model could be used for other heat exchangers.

Thermal loading by radiant heaters is used in building heating and hot structure design applications. In this research, characteristics of the thermal radiative heating of an enclosure by a distinct heater are investigated from the second law of thermodynamics point of view. The governing equations of conservation of mass, momentum, and energy (fluid and solid) are solved by the finite volume method and the semi-implicit method for pressure linked equations (SIMPLE) algorithm. Radiant heaters are modeled by constant heat flux elements, and the lower wall is held at a constant temperature while the other boundaries are adiabatic. The thermal conductivity and viscosity of the fluid are temperature-dependent, which leads to complex partial differential equations with nonlinear coefficients. The parameter study is done based on the amount of thermal load (presented by heating number) as well as geometrical configuration parameters, such as the aspect ratio of the enclosure and the radia...

About four billion people face severe water scarcity every year around the globe. To provide remedy
to this situation sea water desalination has proven to be one of the most effective ways. A number of proven
technologies are already in existence. However, these methods take help of non-renewable energy sources and thus
using up the non-renewable recourses. This article has a proposed methodology in it which would help in
desalination of water without any use of non-renewable energy sources or any highly expensive material that has
high maintenance costs. A simple desalination process that uses renewable sources of energy to desalinate water is
proposed in this article.

Thermal loading by radiant heaters is used in building heating and hot structure design applications. In this research, characteristics of the thermal radiative heating of an enclosure by a distinct heater are investigated from the second law of thermodynamics point of view. The governing equations of conservation of mass, momentum, and energy (fluid and solid) are solved by the finite volume method and the semi-implicit method for pressure linked equations (SIMPLE) algorithm. Radiant heaters are modeled by constant heat flux elements, and the lower wall is held at a constant temperature while the other boundaries are adiabatic. The thermal conductivity and viscosity of the fluid are temperature-dependent, which leads to complex partial differential equations with nonlinear coefficients. The parameter study is done based on the amount of thermal load (presented by heating number) as well as geometrical configuration parameters, such as the aspect ratio of the enclosure and the radiant heater number. The results present the effect of thermal and geometrical parameters on entropy generation and the distribution field. Furthermore, the effect of thermal radiative heating on both of the components of entropy generation (viscous dissipation and heat dissipation) is investigated.

This work proposes the low power implementation of Viterbi Decoder. Majority of viterbi decoder designs in the past use simple Register Exchange or Traceback method to achieve very high speed and low power decoding respectively, but it suffers from both complex routing and high switching activity. Here simplification is made in survivor memory unit by storing only m-1 bits to identify previous state in the survivor path, and by assigning m-1 registers to decision vectors. This approach eliminates unnecessary shift operations. Also for storing the decoded data only half memory is required than register exchange method. In this paper Hybrid approach that combines both Traceback and Register Exchange schemes has been applied to the viterbi decoder design. By using distance properties of encoder we further modified to minimum transition hybrid register exchange method. It leads to lower dynamic power consumption because of lower switching activity. Dynamic power estimation obtained through gate level simulation indicates that the proposed design reduces the power dissipation of a conventional viterbi decoder design by 30%.

Three stage standalone solar thermal Multi Effect Desalination (MED) pilot plant for remote and arid rural regions of Sultanate of Oman using fixed focus type Scheffler concentrator producing 100 litres per day has been set up at author's institute. Preliminary tests carried out on this plant yielded lower outputs of 60-65 litres per day. Heat loss through high temperature brine discharged at 85 o C was observed as one of the reasons for lower yield. Literature reviewed and analysis shown that desalination outputs can be increased with increased feed water inlet temperature. To recover this heat and preheat the feed water supplied, brine heat recovery unit using counter flow type shell and coil heat exchanger has been proposed in this paper. Helically coiled heat exchanger has been selected for its compactness, higher heat transfer area per unit volume, higher inside heat transfer coefficient and lower fouling rates due to induced turbulence. The operating parameters of this heat exchanger will handle hot brine at 80-85 o C and 1 bar pressure. In the present work, heat load, number of turns, coil length and pressure drop calculations are done for estimating the theoretical values based on heat transfer & fluid mechanics principles using numerical correlations from the literature reviewed. The steady state analysis has shown that that coil pitch,inside tube diameter, mass flow rate through the coil and shell affects the heat transfer rates. Practical dimensional constraints have been taken into consideration while finalising the dimensions of the heat exchanger. Overall effectiveness of 84.6% has been calculated for the proposed heat exchanger.

The step by step derivation to solve heat diffusion on cylindrical and spherical. The derivation using first order differential equation (ODE).

Langkah-langkah penyelesaian persamaan heat diffusion untuk silinder dan sphere menggunakan ordinary differential equation (ODE) orde pertama.

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