Exercise 3 Solution

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GROUP 13 De Donatis Lorenzo - 876178 Santoianni Genny, Nicole - 884523 Stucchi Simone - 874442 Politecnico di Milano Course: Building Energy Modelling 2016/17 Professor: Mario Motta Tutor: Rossano Scoccia BEM Assignment 03_EXE07 - GROUP 13 Thermal zone + FC + thermostat + distribution modelling and simulation Report 1) Design and model the pipes of the water loops The sizing of pipes represents a fundamental step in the design of a system. Their size, in fact, has to be correct in order to avoid noise, erosion and unfavourable pumping costs (in the case they are too small) and installation costs if they are too large. In order to define the diameter of water pipes and water velocity, we used the chart derived from the Darcy-Weisbach equation (using friction factors from the Moody chart equations); a maximum linear pressure loss of 250 [Pa/m] has been considered. The first step was focused on choosing a material to guarantee thermal insulation of the pipe and sizing its thickness according to the given table. In order to guarantee 250 [Pa/m], we need to convert the mass of water of fan-coil that we obtained in the previous assignment from [L/h] in [L/s], so that we can derive the internal diameter of the pipe and the velocity from the Darcy-Weisbach graph; it results: - D = 32 [mm] - V = 0.8 [m/s] Being the velocity below 1.2 [m/s] , it does not generate turbolence. At this point, we chose a value of 0.038 [W/m°C] of thermal conductivity of the insulation, that corresponds to a value of external diameter of 88 [mm]. Below, the table with in evidence the chosen values. Note that the external diameter of our pipe is 32mm, while 28mm is the insulation thickness. GROUP 13 De Donatis Lorenzo - 876178 Santoianni Genny, Nicole - 884523 Stucchi Simone - 874442 We now want to…