Analýza propustnosti HDPE výstroje primárních výměníků tepelných čerpadel typu země - voda pro zemní plyn

Abstract

Field measurements were conducted on real installations of ground-source heat pumps in the past, revealing the presence of methane in the circulation loop. This finding led to the hypothesis of possible methane diffusion from the rock environment through the wall of the primary heat exchanger of the heat pump. This issue is particularly significant in the Moravian-Silesian region, where natural gas deposits and reservoirs are located, and it may be associated with coal seam methane in the Upper Silesian Basin, where occurrences of gaseous and liquid hydrocarbons of various ages in different stratigraphic units have been recorded. The main objective of this dissertation was to verify this hypothesis and evaluate the potential risk of methane penetration into the primary circuit of the heat pump. A review of theories related to the examined problem was conducted, and then a real situation in a borehole was simulated using the RK2 laboratory apparatus with a reaction chamber and an expansion vessel. A total of four tests were carried out: a test of the measuring apparatus's tightness, a permeability test of HDPE without measuring the volume of methane, a permeability test of HDPE with measuring the volume of methane, and a permeability test of HDPE with zero pressure gradient. The next phase of the research included laboratory measurements simulating the penetration of methane through an HDPE pipe sample (a circular sample with a diameter of 3.8 cm and a wall thickness of 3.0 mm) using a permeameter available at the Well Stimulation and Hydrocarbon Reservoirs Laboratory (511). Additionally, further field measurements were conducted on real installations of heat pumps, where the presence of methane was identified using a portable gas detector. After detecting methane, gas samples were taken from the expansion vessels and subjected to laboratory analysis at the Chemical Analysis Laboratory (VŠB-TUO) to identify the origin of the methane.