Cooling performance

Figure 6.8-2 IR cell for liquids and solids to record spectra in the temperature range -180 °C to -1-2.50 °C. 1) Contact for thermocouple 2) Vacuum connection 3) Connection for the window heating 4) Flow through tube 5) attenuation assembly for the cooling performance.

The objective of titis study is to experimentally compare the cooling performance of narrow channels, droplet sprays and arrays of microjets. The comparison is mostly under singlephase conditions. However, some implications of two-phase flow are also discussed. Since details regarding each of the three cooling techniques have been reported elsewhere ([1], [2] and [3]), only a brief description is presented here... 

A comparison of cooling performances of thin film evaporator with the performances of pool boiling and spray cooling techniques is shown in Figure 10. The data for pool boiling and spray cooling are reported by Bar-Cohen et al. [30] and Mudawar [15] for the 3M thermal fluid FC-72, which is quite similar to the 3M thermal fluid HFE-7100 used in the thin film evaporator test data as shown in Figure 10. 

Figure 10 Comparison of cooling performances of thin film evaporator with the performances of pool...

The cooling performance of any tower containing a given depth of filling varies with the water concentration. It has been found that maximum contact and performance are obtained with a tower having a water concentration of 2 to 5 gal/(min ft of ground area). Thus the... 

The water spray cooling achieves a CO-destruction efficiency of 66 % and allows compliance with the applicable legislation. Flue-gas cooling over a heat-exchanger provides better efficiency (98 %). For discussion on cooling performance, see also 4.5.2.1. 

Calculated temperature profiles are shown in Fig. 5.21. By comparison, the 2D model with a heat-transfer resistance at the wall gives slightly higher hot-spot temperatures than the A(r)-model. This implies a somewhat better cooling performance according to the A(r)-model, in spite of the pronounced bypass flow near the membrane and the resulting lower fluid velocity in the core of the bed. In addition to the radially averaged temperature profiles, the results from the one-dimensional model are also depicted in Fig. 5.21a. While the maximal difference between predictions of the two-dimensional models is less than 4K, the one-dimensional model overestimates those results by about... 

An important issue concerns the evaluation of the cooling performance. Usually, the first-law of thermodynamics is used to compare the amount of heat extracted by the impinging spray with the total amount of heat that would be removed if all the mass impinging on the surface vaporized (sensible and latent heat components) ... 

Jang and Choi [26] numerically investigated the cooling performance of a microchannel heat sink with nanofluids. Two kinds of nanofluids were investigated in this study, i.e., d = 6 nm nanoparticles in a copper-water mixture and dp = 2 nm diamond-in-water nanofluid. A theoretical model was employed for the thermal conductivity of nanofluids that accounts for four modes of energy transport the thermal diffusion in the base fluid, the thermal diffusion of nanoparticles, the collision between the nanoparticles, and the nanoconvection due to Brownian motion. Specifically,... 

Figure 10a compares the previous experimental findings [27] with the results of the new model. With the new effective thermal conductivity model, the cooling performance of the microchannel heat sink with nanofluids was considered. The cooling performance of a microchannel heat sink with nanofluids was evaluated in terms of the thermal resistance 0, which is defined as... 

Jang SP, Choi SUS (2006) Cooling performance of a microchannel heat sink with nanofluids. Appl Therm Eng 26 2457-2463... 

This equation is used to calculate specific throughput of the bubble, which is often used as a measure of die and cooling performance. 

L. Kairouani, E. Nahdi. Cooling performance and energy saving of a compression -absorption refrigeration system assisted by geothermal energy. App. Th. Eng. 26(2-3), 2006,288-294. 

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