High Efficiency Hybrid Radiant and Heat Pump Heating Plants for Industrial Buildings: An Energy Analysis

Abstract

A hybrid condensing radiant tubes system coupled to a heat pump to heat a typical industrial building was modeled in three climatic zones of Italy using dynamic simulation software. The heating system was set up by radiant tubes and an air heating system with terminals placed in the building supplied by hot water produced by the condensation of the exhausted of the radiant tubes and by a heat pump with external air heat source. An optimization of the main parameters (nominal power of the heat pump, bivalent temperature in alternative bivalent operation, and peak power of the photovoltaic system) was carried out on the basis of energy performance of the hybrid heating system. The optimal configuration of the hybrid heating system that minimizes the annual amount of total non-renewable primary energy and maximizes the non-renewable primary energy ratio was compared with traditional heating systems for industrial buildings. The energy savings of this innovative solution vary in the range of 40%-80% depending on the climate and the configuration of the system.

Innovative Hybrid Condensing Radiant System for Industrial Heating: An Energy and Economic Analysis

“…Moreover, it allowed for better performance in terms of thermal comfort conditions, especially during the first hours of operation in the morning, as in real application the floor area was not fully available due to the presence of production equipment and warehouses. More recently, the same authors presented a further development of this system by coupling an air-water heat pump to produce a hybrid heating system (condensing radiant tubes + heat pump system, CRT+HP) [40]. In this way, an enhancement of renewable energy utilisation was realized.…”

“…As the main novelty of this study, a further development of previous work [40] is presented: the effects of a different control logic of the hybrid configuration (bivalent parallel) on energy performance are reported by dynamic simulations with TRNSYS rel. 17 software, with and without the presence of the PV plant.…”

“…The energy performances of the four systems are evaluated in a real industrial building whose characteristics in terms of size and thermal properties of opaque and transparent structures of the two thermal zones are described in the previous work [40], and here reported in Tables 1 and 2. The three resorts considered are in very different climatic zones following the Italian DPR 412/93 [45], increasing the number of degree days (DD) (and therefore the heating needs of the building) from zone D (1415 DD) to zone E (2814 DD) to zone F (3376 DD) [46].…”

“…The nominal data of the heat pump, simulated by means of type 941, are reported in Table 3. More details concerning the TRNSYS simulation models of the hybrid (Figure 3) and the reference systems are reported in references [39,40].…”

“…The nominal data of the heat pump, simulated by means of type 941, are reported in Table 3. More details concerning the TRNSYS simulation models of the hybrid (Figure 3) and the reference systems are reported in references [39,40]. The quota of the heating load that is not covered by the heat pump is satisfied by the radiant tubes, considering a minimum load factor for the latter equal to 30%.…”