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Heat Conduction
Published in Suhas V. Patankar, Numerical Heat Transfer and Fluid Flow, 2018
There are many ways of splitting a given expression for S into SC and SPTP. Some of these are illustrated by the following examples. The numbers appearing in these examples have no particular significance. The symbol TP* is used to denote the guess value or the previous-iteration value of TP.
Energetic and exergetic performance simulation of open-type heat pump dryer with next-generation refrigerants
Published in Drying Technology, 2020
A. Singh, J. Sarkar, R. R. Sahoo
A simulation code has been developed in Engineering Equation Solver (EES) platform based on the above mathematical model. The inputs are as follows: initial moisture content of carrot slices, air volume flow rate, inlet air temperature and specific humidity, component specifications, and evaporator and condenser temperatures. The calculation steps are as follows: with the guess value of refrigerant superheat (T1) and the evaporator pressure (P1), all the states points are calculated using compressor, evaporator, and condenser models, and the exact value of T1 has been calculated by Newton-Raphson iteration method based on Equation 21 (Capillary tube model). The flowchart for the entire simulation is given in Figure 5. Then, the humidity ratio and the temperature of the air at inlet and exit to the drying chamber have been calculated based on heater and dryer models. Finally, the different performance parameters of the heat pump dryer have been calculated.
Modifications to ASHRAE's sizing method for vertical ground heat exchangers
Published in Science and Technology for the Built Environment, 2018
Mohammadamin Ahmadfard, Michel Bernier
Figure 2 shows schematically the five-step iteration procedure of the alternative method. A guess value of Li= (Nb× Hi) is first selected. Using this guess value, three g-functions are evaluated based on the proper values of ln(t/ts, i), rb/Hi and B/Hi. The whole g-function curve does not need to be evaluated since only three g-function values corresponding to three time periods, tf − t2, tf − t1 and tf are required in each iteration. In the third step, the three g-functions are used to calculate the effective ground thermal resistances (Equation 4) which are then used, in step 4, to evaluate the required borehole length Lii (Equation 3). This length Lii is then compared to the guessed or the previous length Li. If the two lengths agree to within a certain tolerance ϵ, then the solution is said to have converged. If not, the length Lii is then used as the new guess value for the next iteration.
Heat Pipe Finned Heat Exchanger for Heat Recovery: Experimental Results and Modeling
Published in Heat Transfer Engineering, 2018
Giulia Righetti, Claudio Zilio, Simone Mancin, Giovanni A. Longo
The heat exchanger is divided into a series of ranks. The simulation proceeds by iterating on the overall exchanged heat flow rate: it starts by giving a guess value for the cold air temperature at the heat exchanger exit. Each single rank is then simulated starting from the first one located on the hot air direction. The output values for the first rank become the inputs for the second one, etc. Each local iteration (i.e. the one focused on the single rank) ends when the saturation temperature inside each rank allows the calculated exit temperature of the coil air to suitably approximate the initial guess value (i.e. 0.1 K).