Experimental and modelling evaluation of possible solutions for compact design of producer-gas heat exchangers

Abstract

An experimental and numerical campaign was carried out to investigate the performances of tubes in shell heat exchanger applied to cool down the producer gas of a small-scale commercial wood biomass gasifier built by All Power Labs. Producer gas is contaminated with soot and tars that condensate under 300 °C, for this reason the heat exchanger was designed in order to have an in-situ cleaning mechanism. The heat exchanger was tested both with standard plain tubes and with a set of metal twisted tapes (TT) with the aim of enhancing the heat transfer between producer gas and water. Temperatures and mass flows analyses shown a maximum increase of thermal power output and overall heat transfer coefficient respectively of 19% and 76% when TT are applied to the standard plain tubes in shell heat exchanger. Numerical simulations shown a consistency in the trends giving an average discrepancy with experimental results of the 12%.

Fouling effect in a shell-and-tube heat exchanger with twisted tape inserts applied to a small-scale biomass gasification power plant

“…-the gas conditioning stage, which is composed by a gas/water heat exchanger (henceforth called HX) object of the study, and a filter unit that is used to reduce the particulate matter content and the tar amount in the syngas, avoiding its later condensation in the pipelines downstrams [10]. The original cooling system was replaced with the shell-and-tube HX [11,12] described in the following section. -the power generation unit consists of an internal combustion engine connected to a 30 kVA generator capable of generating both electrical and thermal power, recovering the heat from the engine block and exhaust gases.…”

Energy and Emissions Analysis of Hemp Hurd and Vine Pruning Derived Pellets Used as Fuel in a Commercial Stove for Residential Heating

“…Given the intent of calculating the efficiency comparison between different fuels, together with the flowrates, the temperatures of the different fluids were measured by means of the thermocouple datalogger TC-08 from PicoTech [14]. In particular, T-type thermocouples 1 mm thick were used to measure: the ambient air (1) and combustion air (2) intake temperature; the heat exchanger outlet temperature in three different position (3)(4)(5) in order to average the results; the exhaust gases temperature (6).…”

“…Agri-pellets are not conventional fuels obtained from agricultural and forestry residues that do not have a specific use. While several studies referred to the thermochemical conversion of residual biomasses in the form of pellets or briquettes can be found in literature related to the gasification process [1][2][3][4][5], few studies are related to the combustion of agripellets in domestic stoves. The abundancy of residual biomasses [6][7][8][9] is sometimes higher that common fir or beech used in the standard pellet production chain, but the lack of a proper legislation and optimized supply chain suggests the disposal instead of the thermal valorization [10].…”

A student-driven multilevel approach for increasing energy sustainability of remote areas in the Emilia Romagna Apennines

“…Several groups paid particular attention to the valorization of the chestnut woods maintenance as source for wood stoves and gasification systems that can work with different residual biomasses [10,11]. Gasification systems have higher efficiency respect of wood stoves but have often higher maintenance costs due to the cleaning of the gas conditioning stage [12][13][14][15] from soot and tars [16]. Results showed the successes of empowering master students in experimental and participative didactic projects with the win-win outcome of allowing a learning-by-doing experience together with demonstrating the effectiveness of blended solutions for the social and environmental sustainability of remote areas.…”