thermferm/simulator.c

/*****************************************************************************
 * Copyright (C) 2008-2014
 *   
 * Michiel Broek <mbroek at mbse dot eu>
 *
 * This file is part of the mbsePi-apps
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * mbsePi-apps is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with ThermFerm; see the file COPYING.  If not, write to the Free
 * Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *****************************************************************************/

#include "thermferm.h"
#include "simulator.h"

#ifdef USE_SIMULATOR

extern int		my_shutdown;
extern int		debug;
extern sys_config	Config;

int SIMcooling = 0;
int SIMheating = 0;


#ifdef HAVE_WIRINGPI_H
PI_THREAD (my_simulator_loop)
#else
void *my_simulator_loop(void *threadid)
#endif
{
    simulator_list	*simulator;
    time_t		now, last = (time_t)0;
    int			seconds = 0;
    double		k_room_air, k_beer_air, sqm_room_air, sqm_beer_air, thick_room_air, thick_beer_air, air_heat_transfer, beer_heat_transfer;
    double		air_change, /* beer_change, */ vhc_air = 0.00121 /*, vhc_water = 4.1796 */;

    syslog(LOG_NOTICE, "Thread my_simulator_loop started");
    if (debug)
	fprintf(stdout, "Thread my_simulator_loop started\n");

    for (simulator = Config.simulators; simulator; simulator = simulator->next) {
	/*
	 * Heater and cooler have the air temperature
	 */
	simulator->s_heat_temp = simulator->s_cool_temp = simulator->room_temperature;
    }

    for (;;) {
	for (simulator = Config.simulators; simulator; simulator = simulator->next) {
	    if (my_shutdown)
	    	break;

	    now = time(NULL);
	    if (now != last) {
		last = now;
		/*
		 * Each second
		 */
	    	seconds++;

		/*
	    	 * First, calculate temperature difference between the room and the air in the
	    	 * fridge. We use the volume air to roughly calculate the total area between
	    	 * the in and outside. Calculate the effect and shift the air temperature towards
	    	 * the room temperature.
	    	 */
		sqm_room_air = (cbrtl(simulator->volume_air) * cbrtl(simulator->volume_air) * 6) / 100;	/* square meters all fridge sides */
		thick_room_air = 0.04;	/* 4 cm walls	*/
		k_room_air = 0.03;	/* Polystrene	*/
		air_heat_transfer=(k_room_air * sqm_room_air * (simulator->room_temperature - simulator->air_temperature)) / thick_room_air;
		air_change = (air_heat_transfer / (vhc_air * ((simulator->volume_air - simulator->volume_beer) * 1000))) / 60.0;
		simulator->air_temperature += air_change;

	    	/*
	    	 * If heating, calculate temperature of the heating plate. If heating is off but
	    	 * the plate is warmer then the air, calculate the cooling down temperature.
	    	 * Finally, calculate the new air and plate temperature.
	    	 */
		if (SIMheating) {
		    if (simulator->s_heat_temp < simulator->heater_temp) {
			simulator->s_heat_temp += 0.05;
			if (simulator->s_heat_temp > simulator->air_temperature)
			    simulator->air_temperature += ((simulator->s_heat_temp - simulator->air_temperature) / 100.0);
		    }
		} else {
		    /*
		     * Follow the air temperature
		     */
		    simulator->s_heat_temp -= (simulator->s_heat_temp - simulator->air_temperature) / 25.0;
		}

	    	/* 
	    	 * If cooling, calculate temperature of the cooling plate. If cooling is off but
	    	 * the plate is colder then the air, calculate the warming up temperature.
	    	 * Finsally, calculate the new air and plate temperature.
	    	 */
		if (SIMcooling) {
		    if (simulator->s_cool_temp > simulator->cooler_temp) {
			simulator->s_cool_temp -= 0.05;
			if (simulator->s_cool_temp < simulator->air_temperature)
			    simulator->air_temperature -= ((simulator->air_temperature - simulator->s_cool_temp) / 100.0);
		    }
		} else {
		    simulator->s_cool_temp -= (simulator->s_cool_temp - simulator->air_temperature) / 25.0;
		}

	    	/*
	    	 * Calculate the extra beer temperatur rise to simulate the heat produced by the
	    	 * fermentation process. Peak about one day after start and slowly decrease after
	    	 * that.
	    	 */
		sqm_beer_air = (cbrtl(simulator->volume_beer) * cbrtl(simulator->volume_beer) * 6) / 100; /* Simple, the beer is in a cubic box */
		thick_beer_air = 0.001;
		k_beer_air = 0.5;	/* HDPE */
		beer_heat_transfer=(k_beer_air * sqm_beer_air * (simulator->air_temperature - simulator->beer_temperature)) / thick_beer_air;
		/* beer_change = 0; */

	    	/*
	    	 * Calculate final temperature of the beer and the air.
	    	 */
		// Cheap trick, just follow slowly the air temp.
		simulator->beer_temperature += ((simulator->air_temperature - simulator->beer_temperature) / 500.0);
		simulator->air_temperature += ((simulator->beer_temperature - simulator->air_temperature) / 2500.0);

		syslog(LOG_NOTICE, "air=%.3f beer=%.3f heater=%.3f cooler=%.3f", simulator->air_temperature, simulator->beer_temperature,
				simulator->s_heat_temp, simulator->s_cool_temp);

		if (debug)
		    fprintf(stdout, "sqm_room_air=%f air=%f air_heat_transfer=%f air_change=%f  sqm_beer_air=%f beer=%f beer_heat_transfer=%f\n",
			sqm_room_air, simulator->air_temperature, air_heat_transfer, air_change,
			sqm_beer_air, simulator->beer_temperature, beer_heat_transfer);
	    }
	    usleep(100000);
	}
	usleep(50000);
    }

    syslog(LOG_NOTICE, "Thread my_simulator_loop stopped");
    if (debug)
	fprintf(stdout, "Thread my_simulator_loop stopped\n");
    return 0;
}


#endif