**8. Heat exchanger and thermosyphons**

#### **8.1 Applications**

The sheer variety of heat transfer operations has been demonstrated by a number of researchers in their works dealing with thermoacoustic and thermoelectric devices, rotating heat exchangers, commercial blood oxygenators, soil and deep bore heat exchangers, space craft radiators, and pressurized bubble columns.

#### **8.2 Enhancement of heat transfer**

The procedure to ease heat transfer has been stated by many researchers. The fin technology of extension is quite prevalent in the recent times. An investigation was carried out with fin tubes using liquid crystal display technology and plate finned tube exchanger by infrared thermal imaging, and performance measurement has been reported for a finned tube surface and annular fins. Fins having curly surfaces are examined for humid airflow. In addition to this film-wise condensation on plane low finned tubes, transient conduction in a fin, performance of extruded-serrated and extruded-finned tube bundles, and the features of a multi-pass heat exchanger have also been reported.

#### **8.3 Microscale heat transfer**

A number of applications now employ miniaturization of heat transfer devices: micro-heat pipe arrays, electronic cooling, microturbine, evaporation and boiling in microfin, microheat pipes, microscale temperature measurements, and modeling of microchannel flows [93].

#### **8.4 Effect of fouling**

An investigation has been done to study the effect of gas-side fouling in cross flow. Calcium carbonate fouling effect was studied with a microscale image; mineral fouling in extended tube heat exchangers was studied; the use of polyacrylic acid as anti-scaling and antifouling agent was studied [94–96].

#### **8.5 Systems based on thermosyphon**

Thermosyphons found applications in a variety of heat transfer complications such as space radiators and cooling of structures, solar water heaters, nuclear reactors and system based on geothermal energy, evaporators, preheaters, tiny heat pipes used to cool PC, laptops, and other electronic components [97–100].

### **9. Heat transfer: general applications**

The relationship between the parameters of a fluidized bed and the heat transfer to a body engulf in it [101]. The SIMPLE algorithm [102] was used to simulate a blast furnace, and a relationship has been developed for the heat transfer coefficients on extension walls and hydrowalls of the boilers [103]. A porous radiant recirculated burner (PRRB) concept is developed to reduce losses due to open-flame combustion [104]. Leong studied the effect of latent heat of fusion on thin plates and numerical analysis of temperature change in biscuits using Monte Carlo (MC) method [105].

Multiple papers investigated the thermohydraulics of the cooling flow in nuclear reactors. A model was developed to study heat flux for low flow rates [106]. Interwrapper flow was studied, and its effects were analyzed numerically [107]. In the case of ceramic-coated turbine blades, the heat transfer coefficient does not significantly affect metal temperatures when thermal radiation is in the picture.

### **10. Insolation**

#### **10.1 Solar radiation**

Various perspectives to evaluate solar data using modified modeling have been conducted by researchers. A new correlation between sunshine duration and radiation on the surface of the earth has been derived by Suehrcke [108]. It was found that the correlation is very well established for average value. A correction factor was proposed by Muneer [109] for calibrating the shadow band pyranometer. A model was using upper air humidity to estimate global solar radiation [110].

#### **10.2 Solar air heater**

Numerical solutions were also developed for absorbers in a porous medium, Nusselt number and Reynolds-Rayleigh number correlations for natural convection in an open-ended rectangular channel and models for solar air heater with fins [111]. Collector efficiency was predicted in a simplified manner.

#### **10.3 Solar water heaters**

Novelties in the design of solar water heating application are presented in this subsection. Fourier transform technique has been used to estimate the heat transfer and efficiency of a flat solar plate collector [112]. Double-sided flat plate collector was used to experimentally investigate the reduction in heat losses in comparison to conventional solar collector [113]. An experimental investigation on ICS solar water heart with compound parabolic concentrating integral collector storage system was designed and tested [114]. A 2D concentrator was developed aiming to store solar energy [115].

**13**

*Applications of Heat Transfer Enhancement Techniques: A State-of-the-Art Review*

without swirl has been investigated for heat transfer with fluid flow [119].

A simple monoenergetic operator and the Bhatnagar-Gross-Krook model were presented to estimate heat transfer in a rare gas between parallel plates [120]. A mathematical model of 2D magnetohydrodynamic Prandtl fluid flow over a sheet is examined [121], 3D magnetohydrodynamic Cauchy problem has been investigated [122], 2D pseudo-steady compressible magnetohydrodynamic system is studied for expansion of gas in vacuum [123], bio-convection flow of nanofluid is studied in magnetic field [124], and numerical analysis of MHD flow over vertical rotating cone is investigated. Also, the volume of fluid method is used to investigate the MHD of incompressible flow, and MHD fluid behavior is studied for flow and heat

In this review article, an effort has been made to study the recent development in the field of heat transfer enhancement. A lot of experimental and numerical research have been done to study the aspect of heat transfer in different fields such as channel flow, crystal growth, heat exchangers, thermosyphons, phase change materials, temperature and velocity measurement, solar energy, etc. The effect of geometry such as channel modification through inserts, roughness, etc. and external power such as magnetic field, electric field, ultrasound, etc. on the thermal performance and augmentation of heat transfer has been studied. In addition to this, the lattice Boltzmann method, WKB method, numerical inverse method, k-epsilon, Cattaneo-Vernotte model, Hunt-Trivedi model, and LES model have been studied for different heat transfer applications. Overall this review gives a full-scale

In this section, heat transfer in thermal plasma reactor for nanoparticle synthesis has been investigated through different models [116]. A 3D model of heat transfer in thermal plasma system has been developed to show 3D effect of carrier gas [117]; effects of nucleation temperature were investigated by radio frequency; 2D numerical simulation was developed to show flow and heat transfer in argon gas plasma, temperature gradient, velocity, and concentration to study the nitridation of MoSi2 which was carried in thermal plasma reactor; and numerical simulation model was developed to show the effect of radial injection of gas (with and without swirl) on flow and temperature field [118]. Plasma induced between two electrodes with and

*DOI: http://dx.doi.org/10.5772/intechopen.92873*

**11. Plasma heat transfer and MHD**

**11.2 Magnetohydrodynamics (MHD)**

summary of heat transfer applications.

transfer [125].

**12. Conclusion**

**11.1 Investigation and application**
