SELECTION OF THE LAYOUT AND TECHNICAL AND ECONOMIC JUSTIFICATION OF A HEAT PUMP CLIMATE CONTROL SYSTEM FOR VEHICLE REPAIR PREMISES

Abstract

The article substantiates the layout and operating conditions of a climate control system for vehicle repair premises based on a heat pump and low-temperature thermal energy storage, taking into account the intermittent nature of the thermal load. The relevance of the study is determined by the specific operating conditions of vehicle repair facilities, where frequent gate openings, the entry of cold vehicles, and ventilation requirements cause significant short-term heat losses and complicate the efficient operation of low-temperature heating systems.

A transient heat balance model comprising four interconnected components—indoor air, floor slab, vehicle, and buffer tank—is developed. Buoyancy-driven air exchange through open gates is represented as a nonlinear, time-dependent heat loss mechanism. The model is used to evaluate the dynamic response of the indoor climate system and compare alternative heat emission configurations. The results demonstrate that a combined system consisting of underfloor heating and fan coil units supplied from a common thermal buffer restores the working-zone temperature within 7.7 minutes after gate opening, compared with 62 minutes for underfloor heating alone. The minimum sufficient buffer volume is estimated at approximately 100 litres per 1 kW of heat pump heating capacity, while the recommended supply temperature is 35 °C.

A technical and economic assessment of five heating options is performed, including gas and electric boilers, air-to-water and ground-source heat pumps, and a ground-source heat pump combined with solar collectors and thermal storage. A selection criterion based on minimum levelized heat costs is proposed, subject to constraints on the seasonal performance factor, unmet heating demand, and temperature recovery time. Under the analysed 2026 energy tariffs, the ground-source heat pump achieves a seasonal performance factor of 3.84, exceeding the critical value of 3.54 required for lower operating costs than a gas boiler. However, its economic competitiveness depends on capital investment and energy prices. For facilities without gas supply, heat pump systems demonstrate a discounted payback period of 3–5 years compared with electric heating, alongside a 2.8–4.6-fold reduction in carbon dioxide emissions.

The proposed model and decision-making criterion can be used to select heat pump capacity, thermal storage volume, and heat distribution configurations for vehicle repair facilities, supporting energy-efficient system design under variable operating conditions.