Měření teplot ve vrtech pro tepelná čerpadla

Abstract

The task of this diploma thesis was to assemble a measuring and control (monitoring) system for an underground heat accumulator, create a control program for it and put it into operation. First, an analysis of presently used methods of measuring temperature in geothermal exchangers for heat pumps was carried out and based on data obtained a monitoring system for the currently constructed accumulator was designed. The heat accumulator is formed by 16 energetic boreholes for heating the Earth’s crust and 5 monitoring boreholes for observing the thermal profile. The measured data are sent to and stored at a server located at VŠB. The data will be used for further processing and evaluation. The underground heat accumulator will operate in two modes – charging mode and discharging mode. During the charging mode the accumulator is heated by the redundant heat from the gas cogeneration unit. On the other hand, during the discharging mode it is cooled by the cooling circuit. The tasks of the monitoring system are: measurement of temperatures in the monitoring boreholes at the specified depths, measurement of the heat stored at and taken from the accumulator and a simple control system for charging and discharging. A programmable logic controller B&R X20 was chosen for monitoring and control of the flow rate, the temperature of the medium returning to the cogeneration unit and manipulation with the pumps and ventilators. Two different types of heat sensors are connected to the controller. Resistance temperature sensors PT1000 are used for measuring the temperatures in the system and on the inputs and outputs of the heated boreholes. Digital sensors DALAS communicating over the 1-Wire bus are used for measuring in monitoring boreholes. Calorimeter CALOR 40 was chosen to measure the amount of stored and taken energy. Communication between the controller and the calorimeter is carried out according to the M-Bus protocol on the RS485 line. The system is being tested under normal operation at the moment. Due to the fact that it is quite extensive and is linked to other systems, it was not possible to carry out a single one-time testing.