ČVUT v Praze Fakulta stavební Katedra technických zařízení budov ČVUT v Praze Fakulta stavební Katedra technických zařízení budov SE 20- Heating Control and measurement

What is it - Control sytem ? Device, which changes one or more parameters of the heating system Device, which changes one or more parameters of the heating system temperature temperature Flow rate Flow rate pressure pressure

Why to control heating system Output controll according to actual heat loss Output controll according to actual heat loss Operation safety Operation safety Restriction by operational paremeters of heat source or any element of heating systém Restriction by operational paremeters of heat source or any element of heating systém Hydronic balancing Hydronic balancing

Control circuit Controlled variable x Controlled variable x Manipulated variable y Manipulated variable y Disturbance variable z Disturbance variable z Command variable w Command variable w Controlled system X Z Controller Y Actua tor Feedback W

Manipulation Controlled variable is changed by actuator Controlled variable is changed by actuator No feed-back, no controller No feed-back, no controller Controlled system X Z Actua tor ?

Hand actuated control Controller = man Controller = man Controlled system X Z Y Actu ator Feed back W

Automatic actuated controll w and/or x activates actuator to achieve required value of x w and/or x activates actuator to achieve required value of x Controlled system X Z Regulátor Y Actu ator Feed back W

Control circuit Technical background Control circuit Technical background Measurement of controlled and command variable Measurement of controlled and command variable electronic thermometer, flow meter, pressure meter electronic thermometer, flow meter, pressure meter Controller Controller Compare measured values with required valuesa and activates actuator Compare measured values with required valuesa and activates actuator Actuator Actuator Control valve, shutoff valve, three-way valve Control valve, shutoff valve, three-way valve

Output sampling controllers Manipulated variable – on/off, 0- 0,5-1 Manipulated variable – on/off, 0- 0,5-1 Example: room thermostat Example: room thermostat

Continuous action controllers Manipulated variable vs. Controlled variable = transition characteristic. P - proportional P - proportional I – integral I – integral D – shunt D – shunt T – time delay T – time delay … Fuzzy logic – more variables Fuzzy logic – more variables

Controllers - energy Self actuated controllers Self actuated controllers Energy from the controlled systém Energy from the controlled systém Electronic controllers Electronic controllers Pressured air actuated controllers Pressured air actuated controllers

Actuators Electromagnetic shut-off valves Electromagnetic shut-off valves Control valves Control valves Mixing 3 or 4 way valves Mixing 3 or 4 way valves

Thermostatic valves Common With remote setup With remote sensor Radiator valve

Application of 3way valve

Example of pressure diference control

Measurement in heating Measurement of operation parameters for controll Measurement of operation parameters for controll Pressure, temperature, flow rate Pressure, temperature, flow rate Measurement of heat Measurement of heat Own heat source – indirect measurement of fuel consumption Own heat source – indirect measurement of fuel consumption District heating – flow rate + temperatures District heating – flow rate + temperatures

„Heat measurement“ – distribution of costs for end users Liquid indicators Liquid indicators Heat consumption is proportional to evaporation of the special liquid in the glass tube on the heat emmitter Heat consumption is proportional to evaporation of the special liquid in the glass tube on the heat emmitter 1 year 1 year Electronic indicators Electronic indicators Surface temperature of the heat emmitter + air temperature + evaluation Surface temperature of the heat emmitter + air temperature + evaluation Liquid indicators Liquid indicators Heat consumption is proportional to evaporation of the special liquid in the glass tube on the heat emmitter Heat consumption is proportional to evaporation of the special liquid in the glass tube on the heat emmitter 1 year 1 year Electronic indicators Electronic indicators Surface temperature of the heat emmitter + air temperature + evaluation Surface temperature of the heat emmitter + air temperature + evaluation